Techniques for synchronization in wireless communications

ABSTRACT

This application discloses a synchronization signal sending method and a related device. The method includes: generating, a first synchronization signal sequence and a second synchronization signal sequence, where the first synchronization signal sequence is a sequence obtained based on a first m-sequence, the second synchronization signal sequence is a sequence obtained based on a Gold sequence, the Gold sequence is generated based on a second m-sequence and a third m-sequence, and a generator polynomial of the first m-sequence is the same as a generator polynomial of the second m-sequence; mapping, the first synchronization signal sequence onto M subcarriers in a first time unit to obtain a first synchronization signal, and mapping the second synchronization signal sequence onto M subcarriers in a second time unit to obtain a second synchronization signal, where M and N are positive integers greater than 1.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/411,804, filed on May 14, 2019, which is a continuation ofInternational Application No. PCT/CN2018/085740, filed on May 4, 2018,which claims priority to Chinese Patent Application No. 201710309975.6,filed on May 4, 2017. All of the afore-mentioned patent applications arehereby incorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and in particular,to a synchronization signal sending method, a synchronization signalreceiving method, and a related device.

BACKGROUND

In a next-generation radio access network (new radio, NR), a downlinkbase station completes coarse downlink time and frequencysynchronization by using a synchronization signal. The synchronizationsignal includes a primary synchronization signal (PSS) and a secondarysynchronization signal (SSS). User equipment (UE) may receive theprimary synchronization signal and the secondary synchronization signal,to implement synchronization and obtain cell identification information.The user equipment first detects the primary synchronization signal todetermine a center frequency and basic time and frequencysynchronization information or parts of cell identification information,and then obtains the cell identification information by using thesecondary synchronization signal. Usually, there may be a small quantityof possible different primary synchronization signals, for example,three primary synchronization signals or one primary synchronizationsignal. The 3rd Generation Partnership Project (3GPP) discussedgeneration of a primary synchronization signal by using a longest linearfeedback shift register sequence. In addition, a secondarysynchronization signal may also be generated based on a scrambledm-sequence or a Gold sequence. The m-sequence is short for a longestlinear shift register sequence. Usually, to distinguish between theprimary synchronization signal and the secondary synchronization signal,a primary synchronization signal sequence and a secondarysynchronization signal sequence are different.

In a fifth-generation mobile communications technology (5G), a length ofa new synchronization signal sequence may be greater than or equal to alength of a synchronization signal sequence in Long Term Evolution(LTE). An orthogonal frequency division multiplexing technology (OFDM)is used to transmit a synchronization signal. That is, a primarysynchronization signal sequence is mapped onto a subcarrier in an OFDMsystem that is allocated to a primary synchronization signal, and asecondary synchronization signal sequence is mapped onto a subcarrier inthe OFDM system that is allocated to a secondary synchronization signal.

In an existing solution, the primary synchronization signal and thesecondary synchronization signal occupy one OFDM symbol, and sizes ofoccupied bandwidths are the same and are N, where N is an integer, forexample, 127. When a network device detects a primary synchronizationsignal, a secondary synchronization signal in another cell or in a localcell interferes with detection of the primary synchronization signal.

SUMMARY

Embodiments of this application provide a synchronization signal sendingmethod and a synchronization signal receiving method, so as to reducecorrelation between a secondary synchronization signal and a primarysynchronization signal, and reduce interference to the primarysynchronization signal.

A first aspect of an embodiment of this application provides asynchronization signal sending method. The method includes: generating,by a network device, a first synchronization signal sequence that isobtained based on a first m-sequence and a second synchronization signalsequence that is obtained based on a first Gold sequence, where thefirst Gold sequence is generated based on a second m-sequence and athird m-sequence, a generator polynomial of the first m-sequence is thesame as a generator polynomial of the second m-sequence, and the firstm-sequence, the second m-sequence, and the third m-sequence each have alength of N, where N is a positive integer greater than 1; mapping, bythe network device, the first synchronization signal sequence onto Msubcarriers in a first time unit to obtain a first synchronizationsignal, and mapping the second synchronization signal sequence onto Msubcarriers in a second time unit to obtain a second synchronizationsignal, where M is a positive integer greater than 1; and sending, bythe network device, the first synchronization signal and the secondsynchronization signal. In this embodiment of this application, thenetwork device generates the first synchronization signal sequence andthe second synchronization signal sequence that have a small correlationvalue, namely, a primary synchronization signal sequence and a secondarysynchronization signal sequence, to reduce cross-correlation between asecondary synchronization signal and a primary synchronization signal,thereby reducing interference caused to a primary synchronization signalby a secondary synchronization signal in another cell or in a localcell.

In a first implementation of the first aspect in this embodiment of thisapplication, the first synchronization signal sequence is a sequenceobtained based on the first m-sequence, and the generator polynomial ofthe first m-sequence {c(n)|n=0, 1, 2, . . . , N−1} is g₁(x)=Σ_(i=0)^(K)a_(i)·x^(i), where 0≤i≤K, a_(K)=1, a₀=1, and K is a positive integergreater than or equal to 1; and the first synchronization signalsequence and the first m-sequence satisfy s(n)=1−2·c(n), n=0, 1, 2, . .. , N−1, c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2,n=0, 1, 2, . . . , N−K−1, where s(n) is the first synchronization signalsequence, and c(n) is the first m-sequence. The first synchronizationsignal sequence is limited in this embodiment of this application,thereby improving implementability and operability of this embodiment ofthis application.

In a second implementation of the first aspect in this embodiment ofthis application, the second synchronization signal sequence is asequence obtained based on the first Gold sequence, the first Goldsequence is generated based on a second m-sequence {f₁(n)|n=0, 1, 2, . .. , N−1} and a third m-sequence {f₂(n)|n=0, 1, 2, . . . , N−1}, thegenerator polynomial of the second m-sequence is g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), and a generator polynomial of the third m-sequence isg₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1, b₀=1, c_(K)=1, c₀=1,0≤i≤K, and K is a positive integer greater than or equal to 1; and thefirst Gold sequence, the second m-sequence, and the third m-sequencesatisfy y_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)modN)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1,m=0, 1, 2, . . . , N−1, where y_(m,k)(n) is the second synchronizationsignal sequence, g_(m,k)(n) is the first Gold sequence, m is a relativeshift value between the second sequence f₁(n) and the third sequencef₂(n), and k is a cyclic shift value. The second synchronization signalsequence is defined in this embodiment of this application, therebyimproving implementability and operability of this embodiment of thisapplication.

In a third implementation of the first aspect in this embodiment of thisapplication, the second synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the second synchronization signalsequence, f₁(n) is the second m-sequence, and f₂(n) is the thirdm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the second synchronization signalsequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the secondsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the second synchronizationsignal is provided in this embodiment of this application, therebyincreasing an implementation of this embodiment of this application.

A second aspect of an embodiment of this application provides asynchronization signal receiving method. The method includes: receiving,by user equipment, a first receive signal and a second receive signal;generating, by the user equipment, local synchronization signalsequences, where the local synchronization signal sequences includes afirst local synchronization signal sequence and a second localsynchronization signal sequence, the first local synchronization signalsequence is a sequence obtained based on a first m-sequence, the secondlocal synchronization signal sequence is a sequence obtained based on afirst Gold sequence, the first Gold sequence is generated based on asecond m-sequence and a third m-sequence, a generator polynomial of thefirst m-sequence is the same as a generator polynomial of the secondm-sequence, and the first m-sequence, the second m-sequence, and thethird m-sequence each have a length of N, where N is a positive integergreater than 1; and processing, by the user equipment, the first receivesignal and the second receive signal based on the local synchronizationsignal sequence. In this embodiment of this application, the userequipment processes the first receive signal and the second receivesignal respectively by using the generated first local synchronizationsignal sequence and second local synchronization signal sequence thathave a small correlation value, that is, the user equipment processesthe first reception signal and the second reception signal respectivelyby using a local primary synchronization signal sequence and a localsecondary synchronization signal sequence that have a small correlationvalue, to reduce a probability of false detection of a local secondarysynchronization signal and a local primary synchronization signal,thereby improving performance of detecting the first receive signal andthe second receive signal.

In a first implementation of the second aspect in this embodiment ofthis application, the processing, by the user equipment, the firstreceive signal and the second receive signal based on the localsynchronization signal sequence includes: performing, by the userequipment, correlation processing on the first receive signal based onthe first local synchronization signal sequence; and performing, by theuser equipment, correlation processing on the second receive signalbased on the second local synchronization signal sequence. A process ofprocessing the first receive signal and the second receive signal isrefined in this embodiment of this application, thereby perfecting stepsin this embodiment of this application.

In a second implementation of the second aspect in this embodiment ofthis application, the performing, by the user equipment, correlationprocessing on the first receive signal based on the first localsynchronization signal sequence includes: performing, by the userequipment, correlation processing on the first receive signal based onthe first local synchronization signal sequence, where the first localsynchronization signal sequence is the sequence obtained based on thefirst m-sequence, and the generator polynomial of the first m-sequence{c(n)|n=0, 1, 2, . . . , N−1} is g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), wherea_(K)=1, a₀=1, K is a positive integer greater than or equal to 1, and0≤i≤K; and the first local synchronization signal sequence and the firstm-sequence satisfy s(n)=1−2·c(n), n=0, 1, 2, . . . , N−1, c((n+K)modN)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2, . . . ,N−K−1, where s(n) is the first local synchronization signal sequence,and c(n) is the first m-sequence. The first local synchronization signalsequence is limited in this embodiment of this application, therebyimproving implementability and operability of this embodiment of thisapplication.

In a third implementation of the second aspect in this embodiment ofthis application, the performing, by the user equipment, correlationprocessing on the second receive signal based on the second localsynchronization signal sequence includes: performing, by the userequipment, correlation processing on the second receive signal based onthe second local synchronization signal sequence, where the second localsynchronization signal sequence is the sequence obtained based on thefirst Gold sequence, the first Gold sequence is generated based on asecond m-sequence {f₁(n)|n=0, 1, 2, . . . , N−1} and a third m-sequence{f₂(n)|n=0, 1, 2, . . . , N−1}, the generator polynomial of the secondm-sequence is g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), and a generator polynomialof the third m-sequence is g₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1,b₀=1, c_(K)=1, c₀=1, K is a positive integer greater than or equal to 1,and 0≤i≤K; and the first Gold sequence, the second m-sequence, and thethird m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . ,N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, m is a relative shift value between the sequence f₁(n) and thesequence f₂(n), and k is a cyclic shift value. The first localsynchronization signal sequence is limited in this embodiment of thisapplication, thereby improving implementability and operability of thisembodiment of this application.

In a fourth implementation of the second aspect in this embodiment ofthis application, the second local synchronization signal sequencesatisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the second local synchronization signalsequence, f₁(n) is the second m-sequence, and f₂(n) is the thirdm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that y_(m,k)(n) may also berepresented as y_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)].For simplicity, m+k may be denoted as k₁, that is, k₁=m+k. In this case,y_(m,k)(n) may also be represented as y_(m,k)(n)=[1−2·f₁((n+k₁)modN)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . . . , N−1, k is an integerless than or equal to N−1, and k₁ is an integer less than or equal to2(N−1). Another condition that may be satisfied by the second localsynchronization signal is provided in this embodiment of thisapplication, thereby increasing an implementation of this embodiment ofthis application.

A third aspect of an embodiment of this application provides asynchronization signal sending method. The method includes: generating,by a network device, a first synchronization signal sequence and asecond synchronization signal sequence, where the first synchronizationsignal sequence is a sequence obtained based on a first Gold sequence,the first Gold sequence is a sequence generated based on a firstm-sequence and a second m-sequence, the second synchronization signalsequence is a sequence obtained based on a second Gold sequence, thesecond Gold sequence is a sequence generated based on a third m-sequenceand a fourth m-sequence, generator polynomials of the first m-sequenceand the third m-sequence are the same, generator polynomials of thesecond m-sequence and the fourth m-sequence are the same, a relativeshift value between the first m-sequence and the second m-sequence ism₁, a relative shift value between the third m-sequence and the fourthm-sequence is m₂, m₁≠m₂(mod N), and the first m-sequence, the secondm-sequence, the third m-sequence, and the fourth m-sequence each have alength of N; mapping, by the network device, the first synchronizationsignal sequence onto M subcarriers in a first time unit to obtain afirst synchronization signal, and mapping the second synchronizationsignal sequence onto M subcarriers in a second time unit to obtain asecond synchronization signal, where M and N are positive integersgreater than 1; and sending, by the network device, the firstsynchronization signal and the second synchronization signal. In thisembodiment of this application, the network device generates the firstsynchronization signal sequence and the second synchronization signalsequence that have a small correlation value, namely, a primarysynchronization signal sequence and a secondary synchronization signalsequence, to reduce cross-correlation between a secondarysynchronization signal and a primary synchronization signal, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

In a first implementation of the third aspect in this embodiment of thisapplication, the first synchronization signal sequence is the sequenceobtained based on the first Gold sequence, the first Gold sequence isthe sequence generated based on a first m-sequence f₁(n) and a secondm-sequence f₂(n), the second synchronization signal sequence is thesequence obtained based on the second Gold sequence, the second Goldsequence is generated based on a third m-sequence f₃(n) and the fourthm-sequence f₄(n), and the first Gold sequence, the first m-sequence, andthe second m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, where y_(m,k)(n) isthe first synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and the relative shift value between the first m-sequence andthe second m-sequence is m₁. The second Gold sequence, the thirdm-sequence, and the fourth m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)mod N))mod 2, where y_(m,k)(n) thesecond synchronization signal sequence, g_(m,k)(n) is the second Goldsequence, and the relative shift value between the third m-sequence andthe fourth m-sequence is m₂, where n=0, 1, 2, . . . , N−1, k=0, 1, 2, .. . , N−1, m=0, 1, 2, . . . , N−1, and k is a cyclic shift value. Thegenerator polynomials of the first m-sequence and the third m-sequenceare the same and are g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1, a₀=1, thegenerator polynomials of the second m-sequence and the fourth m-sequenceare the same and are g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1, b₀=1, andm₁≠m₂(mod N) is satisfied. The first synchronization signal sequence andthe second synchronization signal sequence are limited in thisembodiment of this application, thereby improving implementability andoperability of this embodiment of this application.

In a second implementation of the third aspect in this embodiment ofthis application, the first synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the first synchronization signalsequence, f₁(n) is the first m-sequence, and f₂(n) is the secondm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the first synchronization signalsequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the firstsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the first synchronizationsignal is provided in this embodiment of this application, therebyincreasing an implementation of this embodiment of this application.

A fourth aspect of an embodiment of this application provides asynchronization signal receiving method. The method includes: receiving,by user equipment, a first receive signal and a second receive signal;generating, by the user equipment, local synchronization signalsequences, where the local synchronization signal sequence includes afirst local synchronization signal sequence and a second localsynchronization signal sequence, the first local synchronization signalsequence is a sequence obtained based on a first Gold sequence, thefirst Gold sequence is a sequence generated based on a first m-sequenceand a second m-sequence, the second local synchronization signalsequence is a sequence obtained based on a second Gold sequence, thesecond Gold sequence is a sequence generated based on a third m-sequenceand a fourth m-sequence, generator polynomials of the first m-sequenceand the third m-sequence are the same, and generator polynomials of thesecond m-sequence and the fourth m-sequence are the same, where arelative shift value between the first m-sequence and the secondm-sequence is m₁, a relative shift value between the third m-sequenceand the fourth m-sequence is m₂, m₁≠m₂(mod N), the first m-sequence, thesecond m-sequence, the third m-sequence, and the fourth m-sequence eachhave a length of N, and N is a positive integer greater than 1; andprocessing, by the user equipment, the first receive signal and thesecond receive signal based on the local synchronization signalsequence. In this embodiment of this application, the user equipmentprocesses the first receive signal and the second receive signalrespectively by using the generated first local synchronization signalsequence and second local synchronization signal sequence that have asmall correlation value, that is, the user equipment processes the firstreception signal and the second reception signal respectively by using alocal primary synchronization signal sequence and a local secondarysynchronization signal sequence, to reduce a probability of falsedetection of a local secondary synchronization signal and a localprimary synchronization signal, thereby improving performance ofdetecting the first receive signal and the second receive signal.

In a first implementation of the fourth aspect in this embodiment ofthis application, the first local synchronization signal sequence is thesequence obtained based on the first Gold sequence, the first Goldsequence is the sequence generated based on a first m-sequence f₁(n) anda second m-sequence f₂(n), the second local synchronization signalsequence is the sequence obtained based on the second Gold sequence, thesecond Gold sequence is the sequence generated based on a thirdm-sequence f₃(n) and a fourth m-sequence f₄(n), and the first Goldsequence, the first m-sequence, and the second m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, where g_(m,k)(n) is the first Gold sequence, y_(m,k)(n) is thefirst synchronization signal sequence, and the relative shift valuebetween the first m-sequence and the second m-sequence is m₁. The secondGold sequence, the third m-sequence, and the fourth m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)modN))mod 2, where y_(m,k)(n) is the second synchronization signalsequence, g_(m,k)(n) is the second Gold sequence, and the relative shiftvalue between the third m-sequence and the fourth m-sequence is m₂,where n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . ,N−1, and k is a cyclic shift value. The generator polynomials of thefirst m-sequence and the third m-sequence are the same and areg₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1, a₀=1, the generator polynomialsof the second m-sequence and the fourth m-sequence are the same and areg₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1, b₀=1, and m₁≠m₂(mod N) issatisfied. The first local synchronization signal sequence and thesecond local synchronization signal sequence are limited in thisembodiment of this application, thereby improving implementability andoperability of this embodiment of this application.

In a second implementation of the fourth aspect in this embodiment ofthis application, the first local synchronization signal sequencesatisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the first local synchronization signalsequence, f₁(n) is the first m-sequence, and f₂(n) is the secondm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the first local synchronizationsignal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the first localsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the first localsynchronization signal is provided in this embodiment of thisapplication, thereby increasing an implementation of this embodiment ofthis application.

A fifth aspect of an embodiment of this application provides asynchronization signal sending method. The method includes: generating,by a network device, a first synchronization signal sequence and asecond synchronization signal sequence, where the second synchronizationsignal sequence is a sequence obtained based on a first m-sequence and asecond m-sequence, a relative shift value between the first m-sequenceand the second m-sequence is m, a cyclic shift value is p, a value rangeof p does not include a cyclic shift value k strongly correlated to thefirst synchronization signal sequence, and the first m-sequence and thesecond m-sequence each have a length of N; mapping, by the networkdevice, the first synchronization signal sequence onto M subcarriers ina first time unit to obtain a first synchronization signal, and mappingthe second synchronization signal sequence onto M subcarriers in asecond time unit to obtain a second synchronization signal, where M andN are positive integers greater than 1; and sending, by the networkdevice, the first synchronization signal and the second synchronizationsignal. In this embodiment of this application, the network devicegenerates the first synchronization signal sequence and the secondsynchronization signal sequence that have a small correlation value,namely, a primary synchronization signal sequence and a secondarysynchronization signal sequence, to reduce cross-correlation between asecondary synchronization signal and a primary synchronization signal,thereby reducing interference caused to a primary synchronization signalby a secondary synchronization signal in another cell or in a localcell.

In a first implementation of the fifth aspect in this embodiment of thisapplication, the second synchronization signal sequence may be a Goldsequence, and the Gold sequence is a sequence generated based on a firstm-sequence f₁(n) and a second m-sequence f₂(n), and satisfiesy _(m,k)(n)=1−2·g _(m,k)(n),g _(m,k)(n)=(f ₁((n+m+k)mod N)+f ₂((n+k)modN))mod 2,n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1,where y_(m,k)(n) is the second synchronization signal sequence,g_(m,k)(n) is the Gold sequence, and f₁(n) and f₂(n) are m-sequences.The second synchronization signal sequence is limited in this embodimentof this application, thereby improving implementability and operabilityof this embodiment of this application.

A sixth aspect of an embodiment of this application provides asynchronization signal receiving method. The method includes: receiving,by user equipment, a first receive signal and a second receive signal;generating, by the user equipment, local synchronization signalsequences, where the local synchronization signal sequences includes afirst local synchronization signal sequence and a second localsynchronization signal sequence, the second local synchronization signalsequence is a sequence obtained based on a first m-sequence and a secondm-sequence, a relative shift value between the first m-sequence and thesecond m-sequence is m, a cyclic shift value is p, a value range of pdoes not include a cyclic shift value k strongly correlated to the firstsynchronization signal sequence, the first m-sequence and the secondm-sequence each have a length of N, and N is a positive integer greaterthan 1; and processing, by the user equipment, the first receive signaland the second receive signal based on the local synchronization signalsequence. In this embodiment of this application, the user equipmentprocesses the first receive signal and the second receive signalrespectively by using the generated first local synchronization signalsequence and second local synchronization signal sequence that have asmall correlation value, that is, the user equipment processes the firstreception signal and the second reception signal respectively by using alocal primary synchronization signal sequence and a local secondarysynchronization signal sequence, to reduce a probability of falsedetection of a local secondary synchronization signal and a localprimary synchronization signal, thereby improving performance ofdetecting the first receive signal and the second receive signal.

In a first implementation of the sixth aspect in this embodiment of thisapplication, the second local synchronization signal sequence may be aGold sequence, and the Gold sequence is generated based on a firstm-sequence f₁(n) and a second m-sequence f₂(n), and satisfiesy _(m,k)(n)=1−2·g _(m,k)(n),g _(m,k)(n)=(f ₁((n+m+k)mod N)+f ₂((n+k)modN))mod 2,n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1,where y_(m,k)(n) is the second local synchronization signal sequence,g_(m,k)(n) is the Gold sequence, and f₁(n) and f₂(n) are m-sequences.The second local synchronization signal sequence is limited in thisembodiment of this application, thereby improving implementability andoperability of this embodiment of this application.

A seventh aspect of an embodiment of this application provides a networkdevice. The network device includes: a generation unit, a mapping unitand a sending unit. The generation unit is configured to generate afirst synchronization signal sequence and a second synchronizationsignal sequence. The first synchronization signal sequence is a sequenceobtained based on a first m-sequence. The second synchronization signalsequence is a sequence obtained based on a first Gold sequence. Thefirst Gold sequence is generated based on a second m-sequence and athird m-sequence. A generator polynomial of the first m-sequence is thesame as a generator polynomial of the second m-sequence. The firstm-sequence, the second m-sequence, and the third m-sequence each have alength of N. The mapping unit is configured to map the firstsynchronization signal sequence onto M subcarriers in a first time unitto obtain a first synchronization signal, and map the secondsynchronization signal sequence onto M subcarriers in a second time unitto obtain a second synchronization signal, where M and N are positiveintegers greater than 1. The sending unit is configured to send thefirst synchronization signal and the second synchronization signal. Inthis embodiment of this application, the network device generates thefirst synchronization signal sequence and the second synchronizationsignal sequence that have a small correlation value, namely, a primarysynchronization signal sequence and a secondary synchronization signalsequence, to reduce cross-correlation between a secondarysynchronization signal and a primary synchronization signal, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

In a first implementation of the seventh aspect in this embodiment ofthis application, the first synchronization signal sequence is thesequence obtained based on the first m-sequence, and the generatorpolynomial of the first m-sequence {c(n)|n=0, 1, 2, . . . , N−1} isg₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where a_(K)=1, a₀=1, K is a positiveinteger greater than or equal to 1, and 0≤i≤K. The first synchronizationsignal sequence and the first m-sequence satisfy s(n)=1−2·c(n), n=0, 1,2, . . . , N−1, c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)modN)+c(n))mod 2, n=0, 1, 2, . . . , N−K−1, where s(n) is the firstsynchronization signal sequence, and c(n) is the first m-sequence. Thefirst synchronization signal sequence is limited in this embodiment ofthis application, thereby improving implementability and operability ofthis embodiment of this application.

In a second implementation of the seventh aspect in this embodiment ofthis application, the second synchronization signal sequence is asequence obtained based on the first Gold sequence, the first Goldsequence is generated based on a second m-sequence {f₁(n)|n=0, 1, 2, . .. , N−1} and a third m-sequence {f₂(n)|n=0, 1, 2, . . . , N−1}. Thegenerator polynomial of the second m-sequence is g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), and a generator polynomial of the third m-sequence isg₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K isa positive integer greater than or equal to 1, and 0≤i≤K. The first Goldsequence, the second m-sequence, and the third m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . .. , N−1, where y_(m,k)(n) is the second synchronization signal sequence,g_(m,k)(n) is the first Gold sequence, m is a relative shift valuebetween the sequence f₁(n) and the sequence f₂(n), and k is a cyclicshift value. The second synchronization signal sequence is limited inthis embodiment of this application, thereby improving implementabilityand operability of this embodiment of this application.

In a third implementation of the seventh aspect in this embodiment ofthis application, the second synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the second synchronization signalsequence, f₁(n) is the second m-sequence, and f₂(n) is the thirdm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the second synchronization signalsequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·(f₁(n+m+k)mod N)]·[1−2·(f₂(n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the secondsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the second synchronizationsignal is provided in this embodiment of this application, therebyincreasing an implementation of this embodiment of this application.

An eighth aspect of an embodiment of this application provides userequipment. The user equipment includes: a receiving unit, configured toreceive a first receive signal and a second receive signal. A generationunit, configured to generate local synchronization signal sequences,where the local synchronization signal sequences includes a first localsynchronization signal sequence and a second local synchronizationsignal sequence. The first local synchronization signal sequence is asequence obtained based on a first m-sequence, the second localsynchronization signal sequence is a sequence obtained based on a firstGold sequence, the first Gold sequence is generated based on a secondm-sequence and a third m-sequence. A generator polynomial of the firstm-sequence is the same as a generator polynomial of the secondm-sequence, and the first m-sequence, the second m-sequence, and thethird m-sequence each have a length of N, where N is a positive integergreater than 1; and a processing unit, configured to process the firstreceive signal and the second receive signal based on the localsynchronization signal sequence. In this embodiment of this application,the user equipment processes the first receive signal and the secondreceive signal respectively by using the generated first localsynchronization signal sequence and second local synchronization signalsequence that have a small correlation value, that is, the userequipment processes the first reception signal and the second receptionsignal respectively by using a local primary synchronization signalsequence and a local secondary synchronization signal sequence, toreduce a probability of false detection of a local secondarysynchronization signal and a local primary synchronization signal,thereby improving performance of detecting the first receive signal andthe second receive signal.

In a first implementation of the eighth aspect in this embodiment ofthis application, the processing unit includes: a first processingsubunit, configured to perform correlation processing on the firstreceive signal based on the first local synchronization signal sequence;and a second processing subunit, configured to perform correlationprocessing on the second receive signal based on the second localsynchronization signal sequence. A process of processing the firstreceive signal and the second receive signal is refined in thisembodiment of this application, thereby perfecting steps in thisembodiment of this application.

In a second implementation of the eighth aspect in this embodiment ofthis application, the first processing subunit is specificallyconfigured to perform correlation processing on the first receive signalbased on the first local synchronization signal sequence. The firstlocal synchronization signal sequence is the sequence obtained based onthe first m-sequence, and the generator polynomial of the firstm-sequence {c(n)|n=0, 1, 2, . . . , N−1} is g₁(x)=Σ_(i=0)^(K)a_(i)·x^(i), where a_(K)=1, a₀=1, K is a positive integer greaterthan or equal to 1, and 0≤i≤K. The first local synchronization signalsequence and the first m-sequence satisfy s(n)=1−2·c(n), n=0, 1, 2, . .. , N−1, c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2,n=0, 1, 2, . . . , N−K−1, where s(n) is the first local synchronizationsignal sequence, and c(n) is the first m-sequence. The first localsynchronization signal sequence is limited in this embodiment of thisapplication, thereby improving implementability and operability of thisembodiment of this application.

In a third implementation of the eighth aspect in this embodiment ofthis application, the second processing subunit is specificallyconfigured to perform correlation processing on the second receivesignal based on the second local synchronization signal sequence. Thesecond local synchronization signal sequence is the sequence obtainedbased on the first Gold sequence, the first Gold sequence is generatedbased on a second m-sequence {f₁(n)|n=0, 1, 2, . . . , N−1} and a thirdm-sequence {f₂(n)|n=0, 1, 2, . . . , N−1}, the generator polynomial ofthe second m-sequence is g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), and a generatorpolynomial of the third m-sequence is g₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i),where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K is a positive integer greater thanor equal to 1, and 0≤i≤K. The first Gold sequence, the secondm-sequence, and the third m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . ,N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, m is a relative shift value between the sequence f₁(n) and thesequence f₂(n), and k is a cyclic shift value. The first localsynchronization signal sequence is limited in this embodiment of thisapplication, thereby improving implementability and operability of thisembodiment of this application.

In a fourth implementation of the eighth aspect in this embodiment ofthis application, the second local synchronization signal sequencesatisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the second local synchronization signalsequence, f₁(n) is the second m-sequence, and f₂(n) is the thirdm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the second local synchronizationsignal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the secondlocal synchronization signal sequence y_(m,k)(n) may also be representedas y_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1,. . . , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1).That is, n is an integer less than or equal to N−1, k is an integer lessthan or equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the second localsynchronization signal is provided in this embodiment of thisapplication, thereby increasing an implementation of this embodiment ofthis application.

A ninth aspect of an embodiment of this application provides a networkdevice. The network device includes: a generation unit, configured togenerate a first synchronization signal sequence and a secondsynchronization signal sequence, where the first synchronization signalsequence is a sequence obtained based on a first Gold sequence, thefirst Gold sequence is a sequence generated based on a first m-sequenceand a second m-sequence, the second synchronization signal sequence is asequence obtained based on a second Gold sequence, the second Goldsequence is a sequence generated based on a third m-sequence and afourth m-sequence, generator polynomials of the first m-sequence and thethird m-sequence are the same, generator polynomials of the secondm-sequence and the fourth m-sequence are the same, a relative shiftvalue between the first m-sequence and the second m-sequence is m₁, arelative shift value between the third m-sequence and the fourthm-sequence is m₂, m₁≠m₂(mod N), and the first m-sequence, the secondm-sequence, the third m-sequence, and the fourth m-sequence each have alength of N; a mapping unit, configured to: map the firstsynchronization signal sequence onto M subcarriers in a first time unitto obtain a first synchronization signal, and map the secondsynchronization signal sequence onto M subcarriers in a second time unitto obtain a second synchronization signal, where M and N are positiveintegers greater than 1; and a sending unit, configured to send thefirst synchronization signal and the second synchronization signal. Inthis embodiment of this application, the network device generates thefirst synchronization signal sequence and the second synchronizationsignal sequence that have a small correlation value, namely, a primarysynchronization signal sequence and a secondary synchronization signalsequence, to reduce cross-correlation between a secondarysynchronization signal and a primary synchronization signal, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

In a first implementation of the ninth aspect in this embodiment of thisapplication, the first synchronization signal sequence is a sequenceobtained based on the first Gold sequence, the first Gold sequence isgenerated based on a first m-sequence f₁(n) and a second m-sequencef₂(n), the second synchronization signal sequence is the sequenceobtained based on the second Gold sequence, the second Gold sequence isthe sequence generated based on a third m-sequence f₃(n) and a fourthm-sequence f₄(n), and the first Gold sequence, the first m-sequence, andthe second m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, where y_(m,k)(n) isthe first synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and the relative shift value between the first m-sequence andthe second m-sequence is m₁. The second Gold sequence, the thirdm-sequence, and the fourth m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)mod N))mod 2, where g_(m,k)(n) isthe second Gold sequence, and the relative shift value between the thirdm-sequence and the fourth m-sequence is m₂, where n=0, 1, 2, . . . ,N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1, and k is a cyclicshift value. The generator polynomials of the first m-sequence and thethird m-sequence are the same and are g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i),a_(K)=1, a₀=1, the generator polynomials of the second m-sequence andthe fourth m-sequence are the same and are g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), b_(K)=1, b₀=1, and m₁≠m₂(mod N) is satisfied. The firstsynchronization signal sequence and the second synchronization signalsequence are limited in this embodiment of this application, therebyimproving implementability and operability of this embodiment of thisapplication.

In a second implementation of the ninth aspect in this embodiment ofthis application, the first synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the first synchronization signalsequence, f₁(n) is the first m-sequence, and f₂(n) is the secondm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the first synchronization signalsequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the firstsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the first synchronizationsignal is provided in this embodiment of this application, therebyincreasing an implementation of this embodiment of this application.

A tenth aspect of an embodiment of this application provides userequipment. The user equipment includes: a receiving unit, configured toreceive a first receive signal and a second receive signal; a generationunit, configured to generate local synchronization signal sequences,where the local synchronization signal sequences includes a first localsynchronization signal sequence and a second local synchronizationsignal sequence, the first local synchronization signal sequence is asequence obtained based on a first Gold sequence, the first Goldsequence is a sequence generated based on a first m-sequence and asecond m-sequence, the second local synchronization signal sequence is asequence obtained based on a second Gold sequence, the second Goldsequence is a sequence generated based on a third m-sequence and afourth m-sequence, generator polynomials of the first m-sequence and thethird m-sequence are the same, and generator polynomials of the secondm-sequence and the fourth m-sequence are the same, where a relativeshift value between the first m-sequence and the second m-sequence ism₁, a relative shift value between the third m-sequence and the fourthm-sequence is m₂, m₁≠m₂(mod N), the first m-sequence, the secondm-sequence, the third m-sequence, and the fourth m-sequence each have alength of N, and N is a positive integer greater than 1; and aprocessing unit, configured to process the first receive signal and thesecond receive signal based on the local synchronization signalsequence. In this embodiment of this application, the user equipmentprocesses the first receive signal and the second receive signalrespectively by using the generated first local synchronization signalsequence and second local synchronization signal sequence that have asmall correlation value, that is, the user equipment processes the firstreception signal and the second reception signal respectively by using alocal primary synchronization signal sequence and a local secondarysynchronization signal sequence, to reduce a probability of falsedetection of a local secondary synchronization signal and a localprimary synchronization signal, thereby improving performance ofdetecting the first receive signal and the second receive signal.

In a first implementation of the tenth aspect in this embodiment of thisapplication, the first local synchronization signal sequence is asequence obtained based on the first Gold sequence, the first Goldsequence is generated based on a first m-sequence f₁(n) and the secondm-sequence f₂(n), the second local synchronization signal sequence isthe sequence obtained based on the second Gold sequence, the second Goldsequence is the sequence generated based on a third m-sequence f₃(n) andthe fourth m-sequence f₄(n), and the first Gold sequence, the firstm-sequence, and the second m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, where y_(m,k)(n) isthe first synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and the relative shift value between the first m-sequence andthe second m-sequence is m₁. The second Gold sequence, the thirdm-sequence, and the fourth m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)mod N))mod 2, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the secondGold sequence, and the relative shift value between the third m-sequenceand the fourth m-sequence is m₂, where n=0, 1, 2, . . . , N−1, k=0, 1,2, . . . , N−1, m=0, 1, 2, . . . , N−1, and k is a cyclic shift value.The generator polynomials of the first m-sequence and the thirdm-sequence are the same and are g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1,a₀=1, the generator polynomials of the second m-sequence and the fourthm-sequence are the same and are g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1,b₀=1, and m₁≠m₂(mod N) is satisfied. The first local synchronizationsignal sequence and the second local synchronization signal sequence arelimited in this embodiment of this application, thereby improvingimplementability and operability of this embodiment of this application.

In a second implementation of the tenth aspect in this embodiment ofthis application, the first local synchronization signal sequencesatisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the first local synchronization signalsequence, f₁(n) is the first m-sequence, and f₂(n) is the secondm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the first local synchronizationsignal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the first localsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).Another condition that may be satisfied by the first localsynchronization signal is provided in this embodiment of thisapplication, thereby increasing an implementation of this embodiment ofthis application.

An eleventh aspect of an embodiment of this application provides asynchronization signal sending method. The method includes: generating,by a network device, a first synchronization signal sequence and asecond synchronization signal sequence, where the second synchronizationsignal sequence is a sequence obtained based on a first m-sequence and asecond m-sequence, a relative shift value between the first m-sequenceand the second m-sequence is m, a cyclic shift value is p, a value rangeof p does not include a cyclic shift value k strongly correlated to thefirst synchronization signal sequence, and the first m-sequence and thesecond m-sequence each have a length of N; mapping, by the networkdevice, the first synchronization signal sequence onto M subcarriers ina first time unit to obtain a first synchronization signal, and mappingthe second synchronization signal sequence onto M subcarriers in asecond time unit to obtain a second synchronization signal, where M andN are positive integers greater than 1; and sending, by the networkdevice, the first synchronization signal and the second synchronizationsignal. In this embodiment of this application, the network devicegenerates the first synchronization signal sequence and the secondsynchronization signal sequence that have a small correlation value,namely, a primary synchronization signal sequence and a secondarysynchronization signal sequence, to reduce cross-correlation between asecondary synchronization signal and a primary synchronization signal,thereby reducing interference caused to a primary synchronization signalby a secondary synchronization signal in another cell or in a localcell.

In a first implementation of the eleventh aspect in this embodiment ofthis application, the second synchronization signal sequence may be aGold sequence, and the Gold sequence is a sequence generated based on afirst m-sequence f₁(n) and the second m-sequence f₂(n), and satisfiesy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . .. , N−1, where y_(m,k)(n) is the second synchronization signal sequence,g_(m,k)(n) is the Gold sequence, and f₁(n) and f₂(n) are m-sequences.The second synchronization signal sequence is limited in this embodimentof this application, thereby improving implementability and operabilityof this embodiment of this application.

A twelfth aspect of an embodiment of this application provides asynchronization signal receiving method. The method includes: receiving,by user equipment, a first receive signal and a second receive signal;generating, by the user equipment, local synchronization signalsequences, where the local synchronization signal sequences includes afirst local synchronization signal sequence and a second localsynchronization signal sequence, the second local synchronization signalsequence is a sequence obtained based on a first m-sequence and a secondm-sequence, a relative shift value between the first m-sequence and thesecond m-sequence is m, a cyclic shift value is p, a value range of pdoes not include a cyclic shift value k strongly correlated to the firstsynchronization signal sequence, the first m-sequence and the secondm-sequence each have a length of N, and N is a positive integer greaterthan 1; and processing, by the user equipment, the first receive signaland the second receive signal based on the local synchronization signalsequence. In this embodiment of this application, the user equipmentprocesses the first receive signal and the second receive signalrespectively by using the generated first local synchronization signalsequence and second local synchronization signal sequence that have asmall correlation value, that is, the user equipment processes the firstreception signal and the second reception signal respectively by using alocal primary synchronization signal sequence and a local secondarysynchronization signal sequence, to reduce a probability of falsedetection of a local secondary synchronization signal and a localprimary synchronization signal, thereby improving performance ofdetecting the first receive signal and the second receive signal.

In a first implementation of the twelfth aspect in this embodiment ofthis application, the second local synchronization signal sequence maybe a Gold sequence, and the Gold sequence is generated based on a firstm-sequence f₁(n) and the second m-sequence f₂(n), and satisfiesy _(m,k)(n)=1−2·g _(m,k)(n),g _(m,k)(n)=(f ₁((n+m+k)mod N)+f ₂((n+k)modN))mod 2,n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1,where y_(m,k)(n) is the second local synchronization signal sequence,g_(m,k)(n) is the Gold sequence, and f₁(n) and f₂(n) are m-sequences.The second local synchronization signal sequence is limited in thisembodiment of this application, thereby improving implementability andoperability of this embodiment of this application.

A thirteenth aspect of this application provides a computer-readablestorage medium. The computer-readable storage medium storesinstructions, which when executed by a computer, causes the computer toperform the following steps: generating a first synchronization signalsequence and a second synchronization signal sequence, where the firstsynchronization signal sequence is a sequence obtained based on a firstm-sequence, the second synchronization signal sequence is a sequenceobtained based on a first Gold sequence, the first Gold sequence isgenerated based on a second m-sequence and a third m-sequence, agenerator polynomial of the first m-sequence is the same as a generatorpolynomial of the second m-sequence, and the first m-sequence, thesecond m-sequence, and the third m-sequence each have a length of N; andmapping the first synchronization signal sequence onto M subcarriers ina first time unit to obtain a first synchronization signal, and mappingthe second synchronization signal sequence onto M subcarriers in asecond time unit to obtain a second synchronization signal, where M andN are positive integers greater than 1.

Optionally, the first synchronization signal sequence is a sequenceobtained based on the first m-sequence, and the generator polynomial ofthe first m-sequence {c(n)|n=0, 1, 2, . . . , N−1} is g₁(x)=Σ_(i=0)^(K)a_(i)·x^(i), where a_(K)=1, a₀=1, K is a positive integer greaterthan or equal to 1, and 0≤i≤K. The first synchronization signal sequenceand the first m-sequence satisfy s(n)=1−2·c(n), n=0, 1, 2, . . . , N−1,c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2,. . . , N−K−1, where s(n) is the first synchronization signal sequence,and c(n) is the first m-sequence.

Optionally, the second synchronization signal sequence is a sequenceobtained based on the first Gold sequence, the first Gold sequence isgenerated based on a second m-sequence {f₁(n)|n=0, 1, 2, . . . , N−1}and a third m-sequence {f₂(n)|n=0, 1, 2, . . . , N−1}, the generatorpolynomial of the second m-sequence is g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i),and a generator polynomial of the third m-sequence is g₃(x)=Σ_(i=0)^(K)c_(i)·x^(i), where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K is a positiveinteger greater than or equal to 1, and 0≤i≤K. The first Gold sequence,the second m-sequence, and the third m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . .. , N−1, where y_(m,k)(n) is the second synchronization signal sequence,g_(m,k)(n) is the first Gold sequence, m is a relative shift valuebetween the sequence f₁(n) and the sequence f₂(n), and k is a cyclicshift value.

Optionally, the second synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the second synchronization signalsequence, f₁(n) is the second m-sequence, and f₂(n) is the thirdm-sequence. It may be understood that x₁(n)=1−2·f₁(n) andx₂(n)=1−2·f₂(n) are substituted into y_(m,k)(n)=x₁((n+m+k)modN)·x₂((n+k)mod N), so as to learn that the second synchronization signalsequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be denoted as k₁, that is, k₁=m+k. In this case, the secondsynchronization signal sequence y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+k₁)mod N)]·[1−2·f₂((n+k)mod N)], where n=0, 1, . .. , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . , 2(N−1). Thatis, n is an integer less than or equal to N−1, k is an integer less thanor equal to N−1, and k₁ is an integer less than or equal to 2(N−1).

Optionally, local synchronization signal sequences is generated. Thelocal synchronization signal sequences includes a first localsynchronization signal sequence and a second local synchronizationsignal sequence. The first local synchronization signal sequence is asequence obtained based on a first m-sequence, the second localsynchronization signal sequence is a sequence obtained based on a firstGold sequence, the first Gold sequence is generated based on a secondm-sequence and a third m-sequence, a generator polynomial of the firstm-sequence is the same as a generator polynomial of the secondm-sequence, and the first m-sequence, the second m-sequence, and thethird m-sequence each have a length of N, where N is a positive integergreater than 1. The first receive signal and the second receive signalare processed based on the local synchronization signal sequence.

It can be learned from the foregoing technical solutions that theembodiments of this application have the following advantages:

In the technical solutions provided in the embodiments of thisapplication, the network device generates the first synchronizationsignal sequence and the second synchronization signal sequence. Thefirst synchronization signal sequence is a sequence obtained based on anm-sequence, the second synchronization signal sequence is a sequenceobtained based on a Gold sequence, the Gold sequence is generated basedon a first m-sequence and a second m-sequence, and a generatorpolynomial of the m-sequence is the same as a generator polynomial ofthe first m-sequence of the Gold sequence. The network device maps thefirst synchronization signal sequence and the second synchronizationsignal sequence respectively onto N subcarriers in the first time unitand N subcarriers in the second time unit, to obtain the firstsynchronization signal and the second synchronization signal, where N isa positive integer greater than or equal to 1. The network device sendsthe first synchronization signal and the second synchronization signal.In the embodiments of this application, a primary synchronization signalsequence and a secondary synchronization signal sequence that have asmall correlation value and that are generated by the network devicereduce cross-correlation between a secondary synchronization signal anda primary synchronization signal, thereby reducing interference causedto a primary synchronization signal by a secondary synchronizationsignal in another cell or in a local cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a schematic diagram of a network architecture according to anembodiment of this application;

FIG. 1b is a schematic diagram of a scenario according to an embodimentof this application;

FIG. 2 is a schematic diagram of a synchronization signal sending methodaccording to an embodiment of this application;

FIG. 3 is a schematic diagram of a correspondence between an octal valueand a primitive polynomial according to an embodiment of thisapplication;

FIG. 4 is a schematic diagram of a scenario in which a synchronizationsignal has different center frequencies according to an embodiment ofthis application;

FIG. 5 is a schematic diagram of a synchronization signal sending methodaccording to another embodiment of this application;

FIG. 6 is a schematic diagram of a network device according to anembodiment of this application;

FIG. 7 is a schematic diagram of user equipment according to anembodiment of this application;

FIG. 8 is a schematic diagram of a network device according to anotherembodiment of this application;

FIG. 9 is a schematic diagram of user equipment according to anotherembodiment of this application;

FIG. 10 is a schematic diagram of a network device according to anotherembodiment of the present invention;

FIG. 11 is a schematic diagram of user equipment according to anotherembodiment of this application;

FIG. 12a is a schematic diagram of user equipment according to anotherembodiment of this application;

FIG. 12b is a schematic diagram of user equipment according to anotherembodiment of this application; and

FIG. 13 is a schematic diagram of a network device according to anotherembodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of this application provide a synchronization signal sendingmethod, so as to reduce correlation between a secondary synchronizationsignal and a primary synchronization signal, and reduce interference tothe primary synchronization signal.

To make persons skilled in the art understand the technical solutions inthis application better, the following describes the embodiments of thisapplication with reference to the accompanying drawings in theembodiments of this application.

In the specification, claims, and accompanying drawings of thisapplication, the terms “first”, “second”, “third”, “fourth”, and so on(if existent) are intended to distinguish between similar objects but donot necessarily indicate a specific order or sequence. It should beunderstood that the data termed in such a way are interchangeable inproper circumstances so that the embodiments described herein can beimplemented in other orders than the order illustrated or describedherein. Moreover, the terms “include”, “have” and any other variantsmean to cover the non-exclusive inclusion, for example, a process,method, system, product, or device that includes a list of steps orunits is not necessarily limited to those steps or units, but mayinclude other steps or units not expressly listed or inherent to such aprocess, method, system, product, or device.

The embodiments of this application may be applied to a networkarchitecture shown in FIG. 1a . In the network architecture, asynchronization signal is transmitted between a network device (forexample, a base station) and user equipment (for example, a mobilephone). A device transmitting a synchronization signal in thisapplication is referred to as a network device. The embodiments of thisapplication are described by using an example in which a network devicesends a synchronization signal to user equipment. As shown in FIG. 1b ,when a user terminal in a cell 1 detects a primary synchronizationsignal, secondary synchronization signals in the cell 1 and a cell 2cause interference to the primary synchronization signal in the cell 1.Because the cell 2 and the cell 1 may not synchronize in time, thesecondary synchronization signal in the cell 2 and the primarysynchronization signal in the cell 1 may overlap with each other interms of time. In this case, the secondary synchronization signal in thecell 2 causes interference to the primary synchronization signal in thecell 1. The secondary synchronization signal in the cell 1 may alsocause interference to detection of the primary synchronization signal inthe cell 1. This is because when detects the primary synchronizationsignal in the cell 1, the user terminal performs correlation operationon a received signal by using a local primary synchronization signalsequence. If a received signal is a secondary synchronization signal,the correlation operation on sequence for the received secondarysynchronization signal by using local primary synchronization signalsequence is preformed. Consequently, detection for the primarysynchronization signal is interfered by the secondary synchronizationsignal.

It may be understood that a synchronization signal may also be sent andreceived between network devices or between user equipments. This is notspecifically limited herein.

The network device in this application may be any device having awireless transmission and receiving function, and includes, but is notlimited to: a base transceiver station (base transceiver station, BTS)in a Global System for Mobile Communications (Global System for Mobile,GSM) or CDMA, a NodeB (NodeB) in WCDMA, an evolved NodeB (NodeB or eNBor e-NodeB, evolved NodeB) in LTE, a gNodeB (gNodeB or gNB) or atransmission/reception point (transmission reception point, TRP) in NR,a base station of future evolution in 3GPP, an access node in a WiFisystem, a wireless relay node, a wireless backhaul node, and the like.The base station may be a macro base station, a micro base station, apicocell base station, a small cell, a relay station, or the like. Aplurality of base stations can support networks that use a sametechnology mentioned above, or may support networks that use differenttechnologies mentioned above. The base station may include one or moreco-sited or non-co-sited transmission/reception points (Transmissionreceiving point, TRP). The network device may alternatively be a radiocontroller, a centralized unit (centralized unit, CU), and/or adistributed unit (distributed unit, DU) in a cloud radio access network(cloud radio access network, CRAN) scenario. The network device mayalternatively be a server, a wearable device, an in-vehicle device, orthe like. That the network device is a base station is used as anexample below for description. The plurality of network devices may bebase stations of a same type or base stations of different types. Thebase station may communicate with a terminal device, or may communicatewith a terminal device by using a relay station. The terminal device maycommunicate with a plurality of base stations that use differenttechnologies. For example, the terminal device may communicate with abase station supporting an LTE network, may communicate with a basestation supporting a 5G network, or may support a dual connection to abase station in an LTE network and a base station in a 5G network.

In this application, the terminal device is a device having a wirelesstransmission and receiving function, and may be deployed on landincluding an indoor or outdoor environment, in a handheld, wearable, orin-vehicle manner, may be deployed on a water surface (for example, in aship), or may be deployed in air (for example, on an airplane, in aballoon, or on a satellite). The terminal device may be a mobile phone(mobile phone), a tablet computer (Pad), a computer having a wirelesstransmission and receiving function, a virtual reality (virtual reality,VR) terminal device, an augmented reality (augmented reality, AR)terminal device, a wireless terminal related to industrial control(industrial control), a wireless terminal related to self driving (selfdriving), a wireless terminal related to remote medical (remotemedical), a wireless terminal related to a smart grid (smart grid), awireless terminal related to transportation safety (transportationsafety), a wireless terminal related to a smart city (smart city), awireless terminal related to a smart home (smart home), or the like. Theembodiments of this application impose no limitation on an applicationscenario. The user equipment sometimes may also be referred to as aterminal, a terminal device, user equipment (user equipment, UE), anaccess terminal device, a UE unit, a UE station, a mobile station, amobile, a remote station, a remote terminal device, a mobile device, aUE terminal device, a terminal device, a wireless communications device,a UE agent, a UE apparatus, or the like. Further, the terminal may bestationary or movable.

According to a sequence rule, a generator polynomial of an m-sequence isg(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where a_(K)=1, a₀=1, and if the generatorpolynomial is g(x), generated sequence c(n)={c(n)|n=0, 1, 2, . . . ,N−1} satisfies the following recursive relationship: c((n+K)modN)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2, . . . ,N−K−1. An initial state is c(K−1), c(K−2), c(K−3), . . . , c(1), c(0),and the sequence {c(n)|n=0, 1, 2, . . . , N−1} may be obtained based onthe initial status value and a recursion formula. When the generatorpolynomial is a Kth-order primitive polynomial, the obtained sequence isan m-sequence having a length of N=2^(K)−1.

A Gold sequence is a sequence generated by performing modulo 2 additionon a pair of preferred m-sequences. The pair of preferred m-sequencesleads to relatively small cross-correlation between different Goldsequences. f₁(n) and f₂(n) are two m-sequences each having a length ofN, g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2 is a Gold sequencehaving a length of N, where m=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . ,N−1. Variation in m and k leads to generation of a plurality ofdifferent Gold sequences in a same group. One pair of m-sequences in theGold sequences leads to relatively small cross-correlation between thedifferent Gold sequences in the same group.

It is assumed that a generator polynomial of a primary synchronizationsignal sequence is g(x)=x⁷+x⁴+1, that is, c(n+7)=(c(n+4)+c(n))mod 2,where c(n) is an m-sequence. An initial state is 1110110, that is,c(6)=1, c(5)=1, c(4)=1, c(3)=0, c(2)=1, c(1)=1, c(0)=0. The m-sequencemay also be represented as {c(6), c(5), c(4), c(3), c(2), c(1), c(0)}={11 1 0 1 1 0}. Further, after BPSK modulation is performed on them-sequence, the m-sequence is mapped onto N subcarriers. For example,N=127. A modulated primary synchronization signal sequence iss(n)=1−2·c(n), n=0, 1, . . . , N−1. It can be learned that herein, them-sequence c(n) and the primary synchronization signal sequence s(n)each have a length of N. For example, three primary synchronizationsignal sequences may be generated based on cyclically shifted sequencesof c(n) with three cyclic shifts (0, 43, 86). A cyclically shiftedsequence of the sequence {c(n)|n=0, 1, 2, . . . , N−1} is represented as{c((n+p)mod N)|n=0, 1, 2, . . . , N−1}, where p is a cyclic shift value,and p=0, 1, 2, . . . , N−1. For example, if a cyclic shift value p is 0and N=127, the primary synchronization signal sequence is represented ass(n)=1−2·c((n)mod 127). If a cyclic shift value p is 43 and N=127, theprimary synchronization signal sequence is represented ass(n)=1−2·c((n+43)mod 127). If a cyclic shift value p is 86, and N=127,the primary synchronization signal sequence is represented ass(n)=1−2·c((n+86)mod 127).

A secondary synchronization signal sequence is obtained based on asequence g_(m,k)(n) which is generated based on two m-sequences, forexample, may be obtained based on sequences f₁(n) and f₂(n) that aregenerated respectively by using generator polynomials g₁(x)=x⁷+x³+1 andg₂(x)=x³+x²+x+1, where g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod2, and an initial value is 1 1 1 0 1 1 0. Herein, m is a relative shiftvalue between the two m-sequences. For example, m=0, 1, 2, . . . , 126,n=0, 1, 2, . . . , 126. Further, after BPSK modulation is performed onthe Gold sequence, the Gold sequence is mapped onto N subcarriers, whereN=127.

y_(m,k)(n)=1−2·g_(m,k)(n), n=0, 1, . . . , N−1 is a secondarysynchronization signal sequence and is mapped onto N subcarriers.Herein, the primary synchronization signal and the secondarysynchronization signal are located on different OFDM symbols. Forexample, N=127.

When a secondary synchronization signal in a neighboring cell isoverlapped with a primary synchronization signal in a local cell in timedomain, interference is caused to the primary synchronization signal.When the UE detects the primary synchronization signal of the localcell, the secondary synchronization signal and the primarysynchronization signal have a relatively large correlation value. Thisalso causes interference to detection of the primary synchronizationsignal. Specifically, for the foregoing generated Gold sequence of thesecondary synchronization signal, maximum correlation values between asequence for a primary synchronization signal having a cyclic shift of 0and a sequence whose cyclic shift value is k_(m) corresponding to 127relative shift values (m=0, 1, . . . , 126) of the Gold sequence are asfollows: {33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33,29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41,29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29,25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29,33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25,31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33,33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31, 41, 29, 33, 33, 29, 25, 31,41, 29, 33, 33}.

Values of k_(m) are as one of the following:

{20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91,95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20,16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95,25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16,30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25,78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30,91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78,20}.

Usually, a maximum correlation value between different sequences in agroup of Gold sequences is 17. Apparently, the foregoing correlationvalues are much greater than 17, leading to relatively largeinterference caused to the primary synchronization signal by thesecondary synchronization signal.

For convenience of understanding, specific procedures of the embodimentsof this application are described below. Referring to FIG. 2, anembodiment of a synchronization signal sending method according to theembodiments of this application includes the following steps.

201. A network device generates a first synchronization signal sequenceand a second synchronization signal sequence.

The network device generates the first synchronization signal sequenceand the second synchronization signal sequence. The firstsynchronization signal sequence is a sequence obtained based on a firstm-sequence, the second synchronization signal sequence is a sequenceobtained based on a first Gold sequence, the first Gold sequence isgenerated based on a second m-sequence and a third m-sequence, agenerator polynomial of the first m-sequence is the same as a generatorpolynomial of the second m-sequence, and the first m-sequence, thesecond m-sequence, and the third m-sequence each have a length of N,where N is a positive integer greater than 1.

It should be noted that the first synchronization signal sequence is thesequence obtained based on the first m-sequence. The network deviceobtains an m-sequence {c(n)|n=0, 1, 2, . . . , N−1} based on a generatorpolynomial g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where a value of a coefficientof the polynomial may be 0 or 1, and a_(K)=1, a₀=1, K is a positiveinteger greater than 1, and 0≤i≤K. Then, the network device obtains thefirst synchronization signal sequence s(n)=1−2·c(n), n=0, 1, 2, . . . ,N−1, c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0,1, 2, . . . , N−K−1 based on an initial state value of the firstm-sequence and a recursion formula, where s(n) is the firstsynchronization signal sequence, and c(n) is the first m-sequence. Adifferent initial state value of the first m-sequence leads to adifferent obtained sequence. The initial state value of the firstm-sequence is not limited herein. The second synchronization signalsequence is the sequence obtained based on the first Gold sequence, thefirst Gold sequence is generated based on a second m-sequence{f₁(n)|n=0, 1, 2, . . . , N−1} and a third m-sequence {f₂(n)|n=0, 1, 2,. . . , N−1}, the generator polynomial of the second m-sequence isg₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), and a generator polynomial of the thirdm-sequence is g₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1, b₀=1,c_(K)=1, c₀=1, K is a positive integer greater than 1, and 0≤i≤K. Thefirst Gold sequence, the second m-sequence, and the third m-sequencesatisfy y_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)modN)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1,m=0, 1, 2, . . . , N−1, where g_(m,k)(n) is the first Gold sequence, mis a relative shift value between the sequence f₁(n) and the sequencef₂(n), and k is a cyclic shift value.

It may be understood that when the generator polynomial is a Kth-orderprimitive polynomial, the obtained first synchronization signal sequenceis an m-sequence. The first synchronization signal sequence has a lengthof N, where N=2^(K)−1. For example, when K=7, N=127. K is an integergreater than 1. This is not specifically limited herein. Cyclic shiftmay be performed on the first synchronization signal sequence and thesecond synchronization signal sequence, to obtain other sequences havingsame properties. For example, a sequence obtained after cyclic shift isperformed on the first synchronization signal sequence has a propertythe same as that of the first synchronization signal sequence, and isstill an m signal sequence. After cyclic shift is performed on thesecond synchronization signal sequence, another Gold sequence in a samegroup is obtained. A cyclically shifted sequence satisfies {c((n+p)modN)|n=0, 1, 2, . . . , N−1}, where p is a cyclic shift value, including,but not limited to p=0, 1, 2, . . . , N−1.

For example, when K=7, N is 127. A first synchronization signal sequencecorresponding to a first synchronization signal is a sequence obtainedbased on the first m-sequence. The generator polynomial of the firstm-sequence is g(x)=x⁷+x⁴+1. The recursion formula isc(n+7)=(c(n+4)+c(n))mod 2. The initial state value of the firstm-sequence is {1 1 1 0 1 1 0}. That is, c(6)=1, c(5)=1, c(4)=1, c(3)=0,c(2)=1, c(1)=1, c(0)=0. In other words, {c(6), c(5), c(4), c(3), c(2),c(1), c(0)}={1 1 1 0 1 1 0}. Based on the initial value of the firstm-sequence, a sequence that is of the first synchronization signal andthat has a length of 127 is obtained: {1 1 1 1 1 1 0 0 0 0 1 1 1 0 1 1 11 0 0 1 0 1 1 0 0 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 1 1 1 0 1 0 1 1 0 11 0 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 0 1 1 1 0 0 1 1 1 0 0 1 1 1 1 0 1 1 01 0 0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 1 0 0 1 0 1 0 0 1 1 1 0 0 1 1 1 1 0 11 0}.

As shown in FIG. 3, a second synchronization signal sequencecorresponding to a second synchronization signal is a sequence obtainedbased on the second m-sequence and the third m-sequence. The generatorpolynomial of the second m-sequence is the same as the generatorpolynomial of the first m-sequence of the first synchronization signal.For example, the generator polynomial of the second m-sequence may berepresented as g(x)=x⁷+x⁴+1. A primitive polynomial corresponding to thesecond m-sequence is {1 0 0 1 0 0 0 1}, and corresponds to an octalvalue 221. For example, the generator polynomial of the third m-sequencemay be a generator polynomial corresponding to any one of octal values361, 375, 313, 301, 325, 345, 367, 271, 253, and 203 in FIG. 3, and acoefficient a₇, a₆, . . . , a₁, a₀ is a value corresponding to eachprimitive polynomial (in other words, the foregoing generatorpolynomial) in FIG. 3, where a₇ is a highest bit. For example, a value361 is represented as 1 1 1 1 0 0 0 1 in a binary form, and a generatorpolynomial corresponding to the value is g₂(x)=x⁷+x⁶+x⁵+x⁴+1. Foranother example, an octal value 203 is represented as 1 0 0 0 0 0 1 1 ina binary form, a corresponding generator polynomial is g₂(x)=x⁷+x+1, anda corresponding recursion formula satisfies c₁(i+7)=(c₁(i+1)+c₁(i))mod2.

Optionally, both the first synchronization signal sequence and thesecond synchronization signal sequence are sequences obtained based on aGold sequence. For example, the first synchronization signal sequence isa sequence obtained based on a first Gold sequence, and the first Goldsequence is a sequence generated based on a first m-sequence and asecond m-sequence. The second synchronization signal sequence is asequence obtained based on a second Gold sequence, and the second Goldsequence is a sequence generated based on a third m-sequence and afourth m-sequence. Generator polynomials of the first m-sequence and thethird m-sequence are the same, and generator polynomials of the secondm-sequence and the fourth m-sequence are the same. For example, arelative shift value between the first m-sequence and the secondm-sequence is m₁, a relative shift value between the third m-sequenceand the fourth m-sequence is m₂, and m₁≠m₂(mod N) is satisfied. Thefirst m-sequence, the second m-sequence, the third m-sequence, and thefourth m-sequence each have a length of N, where N=2^(K)−1.

In an implementation, the first synchronization signal sequencey_(m,k)(n) satisfies y_(m,k)(n)=1−2·g_(m,k)(n). The sequence g_(m,k)(n)may be a Gold sequence obtained based on the first m-sequence f₁(n) andthe second m-sequence f₂(n), and g_(m,k)(n)=(f₁((n+m+k)modN)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1,m=0, 1, 2, . . . , N−1, where m is the relative shift value between thesequence f₁(n) and the sequence f₂(n). The second synchronization signalsequence y_(m,k)(n) satisfies y_(m,k)(n)=1−2·g_(m,k)(n). g_(m,k)(n) maybe a Gold sequence obtained based on the third m-sequence f₃(n) and thefourth m-sequence f₄(n), and g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)modN))mod 2. The relative shift value between the third m-sequence f₃(n)and the fourth m-sequence f₄(n) is m₂, n=0, 1, 2, . . . , N−1, k=0, 1,2, . . . , N−1, m=0, 1, 2, . . . , N−1, and k is the cyclic shift value.

The generator polynomials of the first m-sequence and the thirdm-sequence are the same and both are g₁(x), where g₁(x)=Σ_(i=0)^(K)a_(i)·x^(i), a_(K)=1, a₀=1. The generator polynomials of the secondm-sequence and the fourth m-sequence are the same and both are g₂(x),where g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1, b₀=1, and m₁≠m₂(mod N) issatisfied.

202. The network device obtains a first synchronization signal and asecond synchronization signal.

The network device maps the first synchronization signal sequence onto Msubcarriers in a first time unit to obtain the first synchronizationsignal, and maps the second synchronization signal sequence onto Msubcarriers in a second time unit to obtain the second synchronizationsignal, where M is a positive integer greater than 1.

It should be noted that the first synchronization signal and the secondsynchronization signal that are obtained by the network device may besequences obtained after modulation and transformation are performed onm-sequences, or may be generated according to a formula. The firstsynchronization signal satisfies s(n)=1−2·c(n), n=0, 1, . . . , N−1,where N is a positive integer greater than 1, s(n) is the firstsynchronization signal sequence, and c(n) is the first m-sequence.

M=N or M=N−1. When M=N, N elements in a synchronization signal sequenceare mapped onto N subcarriers. When M=N−1, elements other than a centralelement in a synchronization signal sequence are mapped onto N−1subcarriers. A central element in a sequence of a synchronization signalmay be mapped onto a central subcarrier of the synchronization signal ina frequency domain or may not be transmitted. This is not limited in theembodiments of the present invention.

It may be understood that the network device may modulate an m-sequencethrough binary phase shift keying (binary phase shift keying, BPSK), toobtain a modulated and transformed synchronization signal sequence. Thenetwork device may alternatively, including, but not limited to,modulate the synchronization signal sequence by using another modulationscheme.

For example, when the first m-sequence is the sequence {1 1 1 1 1 1 0 00 0 1 1 1 0 1 1 1 1 0 0 1 0 1 1 0 0 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 11 1 0 1 0 1 1 0 1 1 0 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 0 1 1 1 0 0 1 1 1 00 1 1 1 1 0 1 1 0 1 0 0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 1 0 0 1 0 1 0 0 1 11 0 0 1 1 1 1 0 1 1 0} in the foregoing step, a modulated andtransformed sequence is {−1 −1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 1 −1 −1 −1−1 1 1 −1 1 −1 −1 1 1 −1 1 1 −1 1 1 1 −1 1 1 −1 −1 1 1 1 −1 1 −1 −1 −1 1−1 1 −1 −1 1 −1 −1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 −1 1 −1 1 1 −1 −1 −1 1 1−1 −1 −1 1 1 −1 −1 −1 −1 1 −1 −1 1 −1 1 1 1 1 −1 1 −1 1 −1 1 −1 −1 −1 −1−1 1 −1 1 1 −1 1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1 −1 −1 1}. Amodulation process of the first Gold sequence is similar to a modulationprocess of the first m-sequence, and details are not described hereinagain.

203. The network device sends the first synchronization signal and thesecond synchronization signal.

The network device sends the first synchronization signal on asubcarrier carrying the first synchronization signal sequence, and sendsthe second synchronization signal on a subcarrier carrying the secondsynchronization signal sequence.

204. User equipment receives a first receive signal and a second receivesignal.

The user equipment receives a signal sent by the network device, andchooses to receive the first receive signal and the second receivesignal that satisfy a signal quality requirement.

It should be noted that the user equipment may receive a sensed signal,and receive the needed first receive signal and second receive signalfrom a signal whose signal quality satisfies a requirement. The signalquality may include, but not limited to a signal strength, channelquality indication information, and the like.

205. The user equipment generates local synchronization signalsequences.

The user equipment generates local synchronization signal sequences. Thelocal synchronization signal sequence includes a first localsynchronization signal sequence and a second local synchronizationsignal sequence. The first local synchronization signal sequence is asequence obtained based on the first m-sequence, the second localsynchronization signal sequence is a sequence obtained based on thefirst Gold sequence, the first Gold sequence is generated based on asecond m-sequence and a third m-sequence, and the generator polynomialof the first m-sequence is the same as the generator polynomial of thesecond m-sequence in the first Gold sequence.

It should be noted that the first local synchronization signal sequenceis the sequence obtained based on the first m-sequence. The userequipment obtains the first m-sequence {c(n)|n=0, 1, 2, . . . , N−1}based on the generator polynomial g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where avalue of a coefficient of the polynomial may be 0 or 1, a_(K)=1, a₀=1, Kis a positive integer greater than or equal to 1, and 0≤i≤K. Then, theuser equipment obtains the first local synchronization signal sequences(n)=1−2·c(n), n=0, 1, 2, . . . , N−1, c((n+K)mod N)=(Σ_(i=1)^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2, . . . , N−K−1 based onthe initial state value of the first m-sequence and the recursionformula, where s(n) is the first local synchronization signal sequence,and c(n) is the first m-sequence. A different initial state value of thefirst m-sequence leads to a different obtained sequence. The initialstate value of the first m-sequence is not limited herein. The secondlocal synchronization signal sequence is the sequence obtained based onthe first Gold sequence, the Gold sequence is generated based on asecond m-sequence {f₁(n)|n=0, 1, 2, . . . , N−1} and a third m-sequence{f₂(n)|n=0, 1, 2, . . . , N−1}. The generator polynomial of the secondm-sequence is g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), and the generatorpolynomial of the third m-sequence is g₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i),where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K is a positive integer greater thanor equal to 1, and 0≤i≤K. The first Gold sequence, the secondm-sequence, and the third m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . ,N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and m is the relative shift value between the sequence f₁(n)and the sequence f₂(n).

It may be understood that when the generator polynomial is a Kth-orderprimitive polynomial, the obtained first local synchronization signalsequence is an m-sequence, and the first local synchronization signalsequence has a length of N, where N=2^(K)−1. For example, when K=7,N=127. K is an integer greater than 1. This is not specifically limitedherein. Cyclic shift may be performed on the first local synchronizationsignal sequence and the second local synchronization signal sequence, toobtain other sequences having same properties. For example, a sequenceobtained after cyclic shift is performed on the first localsynchronization signal sequence has a property the same as that of thefirst local synchronization signal sequence, and is still an m-sequence.A sequence obtained after cyclic shift is performed on the second localsynchronization signal sequence is still a Gold sequence. A cyclicallyshifted sequence of the sequence {c(n)|n=0, 1, 2, . . . , N−1} satisfies{c((n+p)mod N)|n=0, 1, 2, . . . , N−1}, p=0, 1, 2, . . . , N−1, where pis the cyclic shift value. Alternatively, a cyclically shifted sequenceof the sequence {c(n)|n=0, 1, 2, . . . , N−1} satisfies {c((n−p)modN)|n=0, 1, 2, . . . , N−1}, where p is the cyclic shift value,including, but not limited to p=0, 1, 2, . . . , N−1.

In an implementation, the user equipment generates the localsynchronization signal sequence. The local synchronization signalsequence includes the first local synchronization signal sequence andthe second local synchronization signal sequence, the first localsynchronization signal sequence is a sequence obtained based on thefirst Gold sequence, and the first Gold sequence is the sequencegenerated based on the first m-sequence f₁(n) and the second m-sequencef₂(n). The second local synchronization signal sequence is a sequenceobtained based on the second Gold sequence, the second Gold sequence isthe sequence generated based on a third m-sequence f₃(n) and a fourthm-sequence f₄(n). The first Gold sequence, the first m-sequence, and thesecond m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, where y_(m,k)(n) isthe first synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and the relative shift value between the first m-sequence andthe second m-sequence is m₁. The second Gold sequence, the thirdm-sequence, and the fourth m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)mod N))mod 2, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the secondGold sequence, the relative shift value between the third m-sequence andthe fourth m-sequence is m₂, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . ,N−1, m=0, 1, 2, . . . , N−1, and k is the cyclic shift value. Thegenerator polynomials of the first m-sequence and the third m-sequenceare the same and are g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1, a₀=1, thegenerator polynomials of the second m-sequence and the fourth m-sequenceare the same and are g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1, b₀=1, andm₁≠m₂(mod N) is satisfied. In all embodiments of the present invention,in a case of m₁≠m₂(mod N), when a system includes a plurality ofsecondary synchronization signal sequences, a relative shift value ofeach secondary synchronization signal sequence satisfies m₁≠m₂(mod N).

206. The user equipment processes the first receive signal and thesecond receive signal.

The user equipment processes the first receive signal and the secondreceive signal based on the local synchronization signal sequence. Alocal synchronization signal includes a first local synchronizationsignal and a second local synchronization signal.

It should be noted that a receive signal includes the first receivesignal and the second receive signal, and the user equipment performs acorrelation operation on the receive signal. The first receive signaland the second receive signal may be the same, for example, may besignals received in one period of time, or may be different, forexample, may be signals received in different periods of time.

In this embodiment of this application, the first synchronization signalsequence and the second synchronization signal sequence that have asmall correlation value and that are generated by the network device,namely, a primary synchronization signal sequence and a secondarysynchronization signal sequence, reduce cross-correlation between asecondary synchronization signal and a primary synchronization signal.When the user equipment detects a primary synchronization signal in alocal cell, interference caused to the primary synchronization signal bya secondary synchronization signal in another cell or in the local cellcan be reduced, thereby ensuring that when searching the primarysynchronization signal at different center frequencies, the primarysynchronization signal is not strongly correlated to anothersynchronization signal due to the different frequencies.

It should be noted that mathematical symbols and letters in theembodiments of the present invention impose no limitation on theembodiments of the present invention. For example, in this embodiment ofthe present invention, the first m-sequence is represented by f₁(n), ormay be represented by using another function symbol or a sequencesymbol, such as a(n), a₁(n), or x(n). In a specific implementationprocess, the foregoing sequence may be data that is stored in aparticular order or satisfies a particular relationship and on whichmathematical computation or processing is performed.

As shown in FIG. 4, when primary synchronization detection is performed,it is assumed that a frequency center is a center 1, and a centerlocation of an actually sent synchronization signal is a center 2. If arelative shift value of a Gold sequence used by a primarysynchronization signal and a relative shift value of a Gold sequenceused by a secondary synchronization signal satisfy m₁=m₂(mod N),different shift values k are used for distinguishing. During detection,when an assumed center is different from a center for actuallytransmitting the secondary synchronization signal, parts overlapped in afrequency domain may be completely the same, leading to a relativelylarge correlation value. According to this solution in the embodimentsof the present invention, m₁≠m₂(mod N). Therefore, a correlation valueis relatively small, and interference is relatively small.

It may be understood that processes of processing different receivesignals by the user equipment are different. For example, detection ofthe primary synchronization signal is different from detection of thesecondary synchronization signal. During the detection of the primarysynchronization signal, a receive-side device needs to assume a centerfrequency of the primary synchronization signal, and obtain a receivedsignal based on the assumed center frequency of the primarysynchronization signal, so as to perform a correlation operation on agenerated local primary synchronization signal sequence and the receivedsignal. The detection of the secondary synchronization signal isperformed when the primary synchronization signal has been detected. Thereceive-side device may obtain a center of the secondary synchronizationsignal based on the center of the detected primary synchronizationsignal (the center of the primary synchronization signal is usually thesame as the center of the secondary synchronization signal). A possiblefrequency of the center of the primary synchronization signal isf₀+n×f_(R), where n is an integer, f₀ is an initial frequency, and f_(R)is a channel spacing and may be predefined. For example, the channelspacing f_(R) may be 100 KHz, 180 KHz, 300 KHz, or the like. Inaddition, a value of f_(R) may vary with a frequency band (FrequencyBand). For example, in a case of a high frequency, a frequency below 3GHz, a frequency from 3 GHz to 6 GHz, and a frequency from 6 GHz to 52.6GHz may correspond to different channel spacing values.

There may be a plurality of, for example, three, primary synchronizationsignal sequences. The network device determines to use one of theprimary synchronization signal sequences based on a cell identifier. Inan implementation, it is assumed that there are three primarysynchronization signal sequences, where two of the primarysynchronization signal sequences may be obtained based on twom-sequences, and the other primary synchronization signal sequence maybe obtained based on a Gold sequence. Generator polynomials of the twom-sequences are the same as generator polynomials of two m-sequences fora Gold sequence for generating the secondary synchronization signal.Generator polynomials of two m-sequences for a Gold sequence for theprimary synchronization signal are the same as polynomials of the twom-sequences for the Gold sequence for generating the secondarysynchronization signal. That is, the m-sequences belong to a same groupof Gold sequences. There may also be a plurality of secondarysynchronization signals. Different Gold sequences are generated throughvariation of the relative shift value and a cyclic shift value, and thedifferent Gold sequences may carry cell identification information.

The primary synchronization signal sequence has a length of N, threecyclic shift values of an m-sequence for generating the primarysynchronization signal sequence are {0, a₀, a₁}, where N>a₁>a₀>0. It isassumed that b₀=a₀, b₁=a₁−a₀, and b₂=N−a₁. The primary synchronizationsignal has a subcarrier spacing of Δf, a₀, a₁, f_(R) are selected, sothat all values of i=0, 1, 2 satisfy (b_(i)×Δf)mod f_(R)>Δf andf_(R)−(b_(i)×Δf)mod f_(R)>Δf. For different frequency bands, Δf may bedifferent. However, each frequency band may be unique. That is, eachfrequency band has only one value. Sequences of synchronization signalsin different frequency bands may have a same length.

For example, it is assumed that N=127, Δf=15 KHz, a₀=43, a₁=86, andf_(R)=100 KHz. In this case, b₀=43, b₁=43, b₂=41. Therefore, b₂×Δf modf_(R)=15 KHz does not satisfy (b₂×Δf)mod f_(R)>Δf. In this way, if adeviation between a frequency of the receive-side device and a frequencyof a transmit-side device is larger than one subcarrier, when thereceive-side device assumes the center frequency of the primarysynchronization signal, and searches the primary synchronization signalbased on the assumed center frequency, due to a frequency offset causedby the center frequency, the assumed synchronization signal and theprimary synchronization signal having a cyclic shift of b₀ may haveapproximately 127−b₀=127−42=85 subcarriers overlapped. Even if thecenter frequency is incorrect, there is a relatively large correlationvalue, leading to degraded receiving performance of the receive-sidedevice. If a₀=42, a₁=84, and f_(R)=100 KHz are selected, b₀=42, b₁=42,and b₂=43. (b_(i)×Δf)mod f_(R)=30 KHz, 30 KHz, 45 KHz respectivelycorrespond to i=0, 1, 2.

f_(R)−(b_(i)×Δf)mod f_(R)=70 KHz, 70 KHz, 25 KHz respectively correspondto i=0, 1, 2. A characteristic of being greater than Δf is satisfied.

For another example, if f_(R)=180 KHz, a₀=43, a₁=86, and Δf=30 KHz,b₀=43, b₁=43, and b₂=41.

(b_(i)×Δf)mod f_(R)=30 KHz, 30 KHz, 150 KHz respectively correspond toi=0, 1, 2.

f_(R)−(b_(i)×Δf)mod f_(R)=150 KHz, 150 KHz, 30 KHz respectivelycorrespond to i=0, 1, 2. A characteristic of being greater than Δf isnot satisfied.

If f_(R)=300 KHz, a₀=42, and a₁=84, b₀=42, b₁=42, b₂=43, and Δf=30 KHz.

(b_(i)×Δf)mod f_(R)=60 KHz, 60 KHz, 90 KHz respectively correspond toi=0, 1, 2.

f_(R)−(b_(i)×Δf)mod f_(R)=240 KHz, 240 KHz, 210 KHz respectivelycorrespond to i=0, 1, 2. A characteristic of being greater than Δf issatisfied.

Further, for each frequency band, all of the selected a₀, a₁, and f_(R)need to satisfy (b_(i)×Δf)mod f_(R)>Δf and f_(R)−(b_(i)×Δf)mod f_(R)>Δf,where Δf is a subcarrier spacing of a primary synchronization signal inthe frequency band. During detection of the primary synchronizationsignal, a method or a device for sending or receiving a primarysynchronization signal sequence that satisfies the feature and that isgenerated based on m-sequences whose cyclic shift values are 0, a₀, anda₁ can reduce interference caused by detection of a center frequency ofa synchronization channel.

With reference to FIG. 5, another embodiment of a synchronization signalsending method provided in the embodiments of this application isdescribed.

501. A network device generates a first synchronization signal sequenceand a second synchronization signal sequence.

The network device generates the first synchronization signal sequenceand the second synchronization signal sequence. The secondsynchronization signal sequence is a sequence obtained based on a firstm-sequence and a second m-sequence. A relative shift value between thefirst m-sequence and the second m-sequence of the second synchronizationsignal sequence is obtained and is m, a cyclic shift value is p, and avalue range of p does not include a cyclic shift value k stronglycorrelated to the first synchronization signal sequence. The firstm-sequence and the second m-sequence each have a length of N.

It should be noted that the second synchronization signal sequence is asequence obtained by performing a modulo 2 addition operation on thefirst m-sequence and the second m-sequence. That is, the secondsynchronization signal sequence is generated based on a first m-sequence{f₁(n)|n=0, 1, 2, . . . , N−1} and a second m-sequence {f₂(n)|n=0, 1, 2,. . . , N−1} through the modulo 2 addition operation. A generatorpolynomial of the first m-sequence is g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), anda generator polynomial of the second m-sequence is g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), where a_(K)=1, a₀=1, b_(K)=1, b₀=1, K is a positiveinteger greater than or equal to 1, and 0≤i≤K. The secondsynchronization signal sequence may be obtained based on a Goldsequence, or may not be obtained based on a Gold sequence. The secondsynchronization signal sequence, the first m-sequence, and the secondm-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)modN)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1,m=0, 1, 2, . . . , N−1, where y_(m,k)(n) is the second synchronizationsignal sequence, g_(m,k)(n) may be the Gold sequence, f₁(n) and f₂(n)are m-sequences, m is the relative shift value between the sequencef₁(n) and the sequence f₂(n). When f₁(n) and f₂(n) are a preferredm-sequence pair, g_(m,k)(n) is the Gold sequence.

It may be understood that, to avoid strong correlation between sequencesfor two synchronization signal, the cyclic shift value p used for anm-sequence in a second synchronization signal does not include thecyclic shift value k corresponding to a sequence having a maximumcorrelation value with a sequence for a first synchronization signal. Acorrelation value between two sequences having a same length is definedas an absolute value of a sum of products of conjugates of elements at asame location. For example, when K=7 and N=127, for any one of 127relative shift values, m=0, 1, 2, . . . , 126. The cyclic shift value kthat the second synchronization signal sequence needs to avoid is {20,16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95,25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16,30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25,78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30,91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78,20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91,95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20, 16, 30, 91, 95, 25, 78, 20}.

502. The network device obtains a first synchronization signal and asecond synchronization signal.

The network device maps the first synchronization signal sequence onto Nsubcarriers in a first time unit to obtain the first synchronizationsignal, and maps the second synchronization signal sequence onto Nsubcarriers in a second time unit to obtain the second synchronizationsignal, where N is a positive integer greater than or equal to 1.

It should be noted that the first synchronization signal and the secondsynchronization signal that are obtained by the network device may besequences obtained after modulation and transformation are performed onm-sequences, or may be directly generated according to a formula. Thefirst synchronization signal satisfies s(n)=1−2·c(n), n=0, 1, . . . ,N−1, where N is a positive integer greater than 1, s(n) is the firstsynchronization signal sequence, and c(n) is the first m-sequence. Thesecond synchronization signal is similar to the first synchronizationsignal, and details are not described herein again.

M=N or M=N−1. When M=N, N elements in a synchronization signal sequenceare mapped onto N subcarriers. When M=N−1, elements other than a centralelement in a synchronization signal sequence are mapped onto N−1subcarriers. A central element in a sequence of a synchronization signalmay be mapped onto a central subcarrier of the synchronization signal ina frequency domain or may not be transmitted. This is not limited in theembodiments of the present invention.

It may be understood that the network device may modulate an m-sequencethrough binary phase shift keying (binary phase shift keying, BPSK), toobtain a modulated and transformed synchronization signal sequence. Thenetwork device may alternatively modulate the synchronization signalsequence by using another modulation scheme. This is not specificallylimited herein.

503. The network device sends the first synchronization signal and thesecond synchronization signal.

The network device sends the first synchronization signal on asubcarrier carrying the first synchronization signal sequence, and sendsthe second synchronization signal on a subcarrier carrying the secondsynchronization signal sequence.

504. User equipment receives a first receive signal and a second receivesignal.

The user equipment performs screening on a received signal, and choosesto receive the first receive signal and the second receive signal thatsatisfy a signal quality requirement.

In this embodiment of this application, step 503 and step 504 in whichthe user equipment transmits the synchronization signals are similar tostep 203 and step 204 in FIG. 2, and details are not described hereinagain.

505. The user equipment generates local synchronization signalsequences.

The user equipment generates the local synchronization signal sequences.The local synchronization signal sequence includes a first localsynchronization signal sequence and a second local synchronizationsignal sequence. The second local synchronization signal sequence is asequence obtained based on the first m-sequence and the secondm-sequence. The relative shift value between the first m-sequence andthe second m-sequence of the second local synchronization signalsequence is obtained and is m. The cyclic shift value is p, and thevalue range of p does not include the cyclic shift value k stronglycorrelated to the first synchronization signal sequence.

It may be understood that the second local synchronization signalsequence may be obtained based on a Gold sequence. The Gold sequence isa sequence generated based on a first m-sequence f₁(n) and a secondm-sequence f₂(n). The second local synchronization signal sequencesatisfies y_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)modN)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1,m=0, 1, 2, . . . , N−1.

506. The user equipment processes the first receive signal and thesecond receive signal.

The user equipment processes the first receive signal and the secondreceive signal based on the local synchronization signal sequence. Alocal synchronization signal includes a first local synchronizationsignal and a second local synchronization signal.

It should be noted that a receive signal includes the first receivesignal and the second receive signal, and the user equipment performs acorrelation operation on the receive signal.

In this embodiment of this application, the first synchronization signalsequence and the second synchronization signal sequence that have smallcorrelation value and that are generated by the network device, namely,a primary synchronization signal sequence and a secondarysynchronization signal sequence, reduce cross-correlation between asecondary synchronization signal and a primary synchronization signal.In this way, when the user equipment detects a primary synchronizationsignal in a local cell, interference caused to the primarysynchronization signal by a secondary synchronization signal in anothercell or in the local cell can be reduced.

Referring to FIG. 6, an embodiment of a network device in theembodiments of this application includes:

a generation unit 601, configured to generate a first synchronizationsignal sequence and a second synchronization signal sequence, where thefirst synchronization signal sequence is a sequence obtained based on afirst m-sequence, the second synchronization signal sequence is asequence obtained based on a first Gold sequence. The first Goldsequence is generated based on a second m-sequence and a thirdm-sequence, a generator polynomial of the first m-sequence is the sameas a generator polynomial of the second m-sequence, and the firstm-sequence, the second m-sequence, and the third m-sequence each have alength of N;

a mapping unit 602, configured to: map the first synchronization signalsequence onto M subcarriers in a first time unit to obtain a firstsynchronization signal, and map the second synchronization signalsequence onto M subcarriers in a second time unit to obtain a secondsynchronization signal, where M and N are positive integers greater than1; and

a sending unit 603, configured to send the first synchronization signaland the second synchronization signal.

This embodiment of the present invention provides a method forgenerating a synchronization signal. The synchronization signal mayinclude the first synchronization signal and the second synchronizationsignal. The first synchronization signal and the second synchronizationsignal may be the first synchronization signal and the secondsynchronization signal mentioned in the embodiments of this application.For example, the first synchronization signal may be a primarysynchronization signal, and the second synchronization signal may be asecondary synchronization signal. The first synchronization signal isgenerated based on a first synchronization signal sequence. The secondsynchronization signal is generated based on a second synchronizationsignal sequence.

In a possible implementation, the first synchronization signal sequences(n) satisfies s(n)=1−2·c(n), n=0, 1, 2, . . . , N−1, where c(n) is thefirst m-sequence. The generator polynomial of the first m-sequence{c(n)|n=0, 1, 2, . . . , N−1} is g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), wherea_(K)=1, a₀=1, K is a positive integer greater than or equal to 1, and0≤i≤K. c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0,1, 2, . . . , N−K−1. The generator polynomial of the first m-sequencec(n) is g(x)=x⁷+x⁴+1. A recursion formula is c(n+7)=(c(n+4)+c(n))mod 2.

In a possible implementation, the second synchronization signal sequencey_(m,k)(n) satisfies y_(m,k)(n)=1−2·g_(m,k)(n), n=0, 1, 2, . . . , N−1,where g_(m,k)(n) is the sequence obtained based on the second m-sequence{f₁(n)|n=0, 1, 2, . . . , N−1} and the third m-sequence {f₂(n)|n=0, 1,2, . . . , N−1}. For example, g_(m,k)(n) may be a Gold sequence. Thegenerator polynomial of the second m-sequence is g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), a generator polynomial of the third m-sequence isg₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K isa positive integer greater than or equal to 1, and 0≤i≤K.g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, n=0, 1, 2, . . . ,N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1, where m is arelative shift value between the sequence f₁(n) and the sequence f₂(n),and k is a cyclic shift value.

In another possible implementation, the second synchronization signalsequence y_(m,k)(n) satisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N)(Formula 1), wherex ₁(n)=1−2·f ₁(n)  (Formula 2);x ₂(n)=1−2·f ₂(n)  (Formula 3); and

n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . , N−1,f₁(n) is the second m-sequence, and f₂(n) the third m-sequence.

It may be understood that the formula 2 and the formula 3 may besubstituted into the formula 1, to obtain:y _(m,k)(n)=[1−2·f ₁((n+m+k)mod N)]˜[1−2·f ₂((n+k)mod N)]  (Formula 4)

For simplicity, m+k may be considered as k₁, that is, k₁=m+k. In thiscase, the formula 4 may also be represented as:y _(m,k)(n)=[1−2·f ₁((n+k ₁)mod N)]·[1−2·f ₂((n+k)mod N)]  (Formula 5),where

n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, and k₁=0, 1, 2, . . . ,2(N−1), that is, n is an integer less than or equal to N−1, k is aninteger less than or equal to N−1, and k, is an integer less than orequal to 2(N−1).

In a possible implementation, the generator polynomial of the firstm-sequence {c(n)|n=0, 1, 2, . . . , N−1} is the same as the generatorpolynomial of the second m-sequence f₁(n). For example, the generatorpolynomial of the first m-sequence is g(x)=x⁷+x⁴+1, and the recursionformula is c(n+7)=(c(n+4)+c(n))mod 2; and the generator polynomial ofthe second m-sequence is g(x)=x⁷+x⁴+1, and a recursion formula isf₁(n+7)=(f₁(n+4)+f₁(n))mod 2.

The first synchronization signal sequence and the second synchronizationsignal sequence that are obtained in this embodiment have a smallcorrelation value. That is, a primary synchronization signal sequenceand a secondary synchronization signal sequence have a small correlationvalue. Therefore, cross-correlation between a secondary synchronizationsignal and a primary synchronization signal can be reduced, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

Referring to FIG. 7, another embodiment of user equipment in theembodiments of this application includes a receiving unit 701, ageneration unit 702, a processing unit 703:

The receiving unit 701, configured to receive a first receive signal anda second receive signal;

The generation unit 702, configured to generate local synchronizationsignal sequences, where the local synchronization signal sequencesincludes a first local synchronization signal sequence and a secondlocal synchronization signal sequence. The first local synchronizationsignal sequence is a sequence obtained based on a first m-sequence. Thesecond local synchronization signal sequence is a sequence obtainedbased on a first Gold sequence, the first Gold sequence is generatedbased on a second m-sequence and a third m-sequence, a generatorpolynomial of the first m-sequence is the same as a generator polynomialof the second m-sequence, and the first m-sequence, the secondm-sequence, and the third m-sequence each have a length of N, where N isa positive integer greater than 1; and

The processing unit 703, configured to process the first receive signaland the second receive signal based on the local synchronization signalsequence.

Optionally, the processing unit 703 may further include:

a first processing subunit 7031, configured to perform correlationprocessing on the first receive signal based on the first localsynchronization signal sequence; and

a second processing subunit 7032, configured to perform correlationprocessing on the second receive signal based on the second localsynchronization signal sequence.

Optionally, the first processing subunit 7031 may be specificallyconfigured to:

perform correlation processing on the first receive signal based on thefirst local synchronization signal sequence, where the first localsynchronization signal sequence is the sequence obtained based on thefirst m-sequence. The first local synchronization signal sequence s(n)satisfies s(n)=1−2·c(n), n=0, 1, 2, . . . , N−1, where c(n) is the firstm-sequence. The generator polynomial of the first m-sequence {c(n)|n=0,1, 2, . . . , N−1} is g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where a_(K)=1,a₀=1, K is a positive integer greater than or equal to 1, and 0≤i≤K.c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2,. . . , N−K−1. The generator polynomial of the first m-sequence c(n) isg(x)=x⁷+x⁴+1. A recursion formula is c(n+7)=(c(n+4)+c(n))mod 2.

Optionally, the first local synchronization signal sequence mayalternatively be generated in a manner of generating the firstsynchronization signal sequence in the foregoing embodiments. Fordetails, refer to related descriptions in the foregoing embodiments.Details are not described herein again.

Optionally, the second processing subunit 7032 may be specificallyconfigured to:

perform correlation processing on the second receive signal based on thesecond local synchronization signal sequence.

In an implementation, the second local synchronization signal sequenceis the sequence obtained based on the first Gold sequence. The firstGold sequence is generated based on a second m-sequence {f₁(n)|n=0, 1,2, . . . , N−1} and a third m-sequence {f₂(n)|n=0, 1, 2, . . . , N−1}.The generator polynomial of the second m-sequence is g₂(x)=Σ_(i=0)^(K)b_(i)·x^(i), and a generator polynomial of the third m-sequence isg₃(x)=Σ_(i=0) ^(K)c_(i)·x^(i), where b_(K)=1, b₀=1, c_(K)=1, c₀=1, K isa positive integer greater than or equal to 1, and 0≤i≤K. The first Goldsequence, the second m-sequence, and the third m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . .. , N−1, where y_(m,k)(n) is the second synchronization signal sequence,g_(m,k)(n) is the first Gold sequence, m is a relative shift valuebetween the sequence f₁(n) and the sequence f₂(n), and k is a cyclicshift value.

In another implementation, the second local synchronization signalsequence y_(m,k)(n) satisfies:y _(m,k)(n)=x ₁((n+m+k)mod N)·x ₂((n+k)mod N,where x₁(n)=1−2·f₁(n), x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2,. . . , N−1, m=0, 1, 2, . . . , N−1, f₁(n) is the second m-sequence, andf₂(n) is the third m-sequence.

It may be understood that y_(m,k)(n) may also be represented as:y _(m,k)(n)=[1−2·f ₁((n+m+k)mod N)]·[1−2·f ₂((n+k)mod N)].

For simplicity, m+k may be considered as k₁, that is, k₁=m+k. In thiscase, y_(m,k)(n) may also be represented as:y _(m,k)(n)=[1−2·f ₁((n+k ₁)mod N)]·[1−2·f ₂((n+k)mod N)]  (Formula 5),where

n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, k₁=0, 1, 2, . . . , 2(N−1),that is, n is an integer less than or equal to N−1, k is an integer lessthan or equal to N−1, and k₁ is an integer less than or equal to 2(N−1).

In a possible implementation, the generator polynomial of the firstm-sequence {c(n)|n=0, 1, 2, . . . , N−1} is the same as the generatorpolynomial of the second m-sequence f₁(n). For example, the generatorpolynomial of the first m-sequence is g(x)=x⁷+x⁴+1, and the recursionformula is c(n+7)=(c(n+4)+c(n))mod 2; and the generator polynomial ofthe second m-sequence is g(x)=x⁷+x⁴+1, and a recursion formula isf₁(n+7)=(f₁(n+4)+f₁(n))mod 2.

Optionally, the second local synchronization signal sequence mayalternatively be generated in a manner of generating the firstsynchronization signal sequence in the foregoing embodiments. Fordetails, refer to related descriptions in the foregoing embodiments.Details are not described herein again.

In this embodiment of this application, the user equipment processes thefirst receive signal and the second receive signal respectively by usingthe generated first local synchronization signal sequence and secondlocal synchronization signal sequence that have a small correlationvalue, that is, the user equipment processes the first reception signaland the second reception signal respectively by using a local primarysynchronization signal sequence and a local secondary synchronizationsignal sequence, to reduce a probability of false detection of a localsecondary synchronization signal and a local primary synchronizationsignal, thereby improving performance of detecting the first receivesignal and the second receive signal.

Referring to FIG. 8, another embodiment of a network device in theembodiments of this application includes a generation unit 801, amapping unit 802, a sending unit 803:

The generation unit 801, configured to generate a first synchronizationsignal sequence and a second synchronization signal sequence, where thefirst synchronization signal sequence is a sequence obtained based on afirst Gold sequence. The first Gold sequence is a sequence generatedbased on a first m-sequence and a second m-sequence. The secondsynchronization signal sequence is a sequence obtained based on a secondGold sequence. The second Gold sequence is a sequence generated based ona third m-sequence and a fourth m-sequence, generator polynomials of thefirst m-sequence and the third m-sequence are the same, generatorpolynomials of the second m-sequence and the fourth m-sequence are thesame. A relative shift value between the first m-sequence and the secondm-sequence is m₁, a relative shift value between the third m-sequenceand the fourth m-sequence is m₂, m₁≠m₂(mod N), and the first m-sequence,the second m-sequence, the third m-sequence, and the fourth m-sequenceeach have a length of N;

The mapping unit 802, configured to: map the first synchronizationsignal sequence onto M subcarriers in a first time unit to obtain afirst synchronization signal, and map the second synchronization signalsequence onto M subcarriers in a second time unit to obtain a secondsynchronization signal, where M and N are positive integers greater than1; and

The sending unit 803, configured to send the first synchronizationsignal and the second synchronization signal.

Optionally, the first synchronization signal sequence is the sequenceobtained based on the first Gold sequence, the first Gold sequence isthe sequence generated based on a first m-sequence f₁(n) and a secondm-sequence f₂(n). The second synchronization signal sequence is thesequence obtained based on the second Gold sequence, the second Goldsequence is the sequence generated based on a third m-sequence f₃(n) anda fourth m-sequence f₄(n), and the first Gold sequence, the firstm-sequence, and the second m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)mod N))mod 2, where y_(m,k)(n) isthe first synchronization signal sequence, g_(m,k)(n) is the first Goldsequence, and the relative shift value between the first m-sequence andthe second m-sequence is m₁. The second Gold sequence, the thirdm-sequence, and the fourth m-sequence satisfy y_(m,k)(n)=1−2·g_(m,k)(n),g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)mod N))mod 2, where y_(m,k)(n) isthe second synchronization signal sequence, g_(m,k)(n) is the secondGold sequence, and the relative shift value between the third m-sequenceand the fourth m-sequence is m₂, where n=0, 1, 2, . . . , N−1, k=0, 1,2, . . . , N−1, m=0, 1, 2, . . . , N−1, and k is a cyclic shift value.The generator polynomials of the first m-sequence and the thirdm-sequence are the same and are g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1,a₀=1, the generator polynomials of the second m-sequence and the fourthm-sequence are the same and are g₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1,b₀=1, and m₁≠m₂(mod N) is satisfied.

Optionally, the first synchronization signal sequence satisfiesy_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), x₁(n)=1−2·f₁(n),x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2,. . . , N−1, where y_(m,k)(n) is the first synchronization signalsequence, f₁(n) is the first m-sequence, and f₂(n) is the secondm-sequence.

It should be noted that the first synchronization signal sequence andthe second synchronization signal sequence in this embodiment may besequences described with reference to the foregoing embodiments.

For example, the first synchronization signal sequence s(n) satisfiess(n)=1−2·c(n), n=0, 1, 2, . . . , N−1, where c(n) is the firstm-sequence. The generator polynomial of the first m-sequence {c(n)|n=0,1, 2, . . . , N−1} is g₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), where a_(K)=1,a₀=1, K is a positive integer greater than or equal to 1, and 0≤i≤K.c((n+K)mod N)=(Σ_(i=1) ^(K−1)a_(i)·c((n+i)mod N)+c(n))mod 2, n=0, 1, 2,. . . , N−K−1.

For another example, the second synchronization signal sequencey_(m,k)(n) satisfies y_(m,k)(n)=x₁((n+m+k)mod N)·x₂((n+k)mod N), wherex₁(n)=1−2·f₁(n), x₂(n)=1−2·f₂(n), n=0, 1, . . . , N−1, k=0, 1, 2, . . ., N−1, m=0, 1, 2, . . . , N−1, f₁(n) is the second m-sequence, and f₂(n)is the third m-sequence. y_(m,k)(n) may also be represented asy_(m,k)(n)=[1−2·f₁((n+m+k)mod N)]·[1−2·f₂((n+k)mod N)]. For simplicity,m+k may be considered as k₁, that is, k₁=m+k. In this case, y_(m,k)(n)may also be represented as:y _(m,k)(n)=[1−2·f ₁((n+k ₁)mod N)]·[1−2·f ₂((n+k)mod N)],where n=0, 1, . . . , N−1, k=0, 1, 2, . . . , N−1, k₁=0, 1, 2, . . . ,2(N−1), that is, n is an integer less than or equal to N−1, k is aninteger less than or equal to N−1, and k₁ is an integer less than orequal to 2(N−1).

In this embodiment of this application, the network device generates thefirst synchronization signal sequence and the second synchronizationsignal sequence that have a small correlation value, namely, a primarysynchronization signal sequence and a secondary synchronization signalsequence, to reduce cross-correlation between a secondarysynchronization signal and a primary synchronization signal, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

Referring to FIG. 9, another embodiment of user equipment in theembodiments of this application includes a receiving unit 901, ageneration unit 902 and a processing unit 903.

The receiving unit 901 is configured to receive a first receive signaland a second receive signal.

The generation unit 902 is configured to generate local synchronizationsignal sequences, where the local synchronization signal sequencesincludes a first local synchronization signal sequence and a secondlocal synchronization signal sequence. The first local synchronizationsignal sequence is a sequence obtained based on a first Gold sequence.The first Gold sequence is a sequence generated based on a firstm-sequence and a second m-sequence. The second local synchronizationsignal sequence is a sequence obtained based on a second Gold sequence.The second Gold sequence is a sequence generated based on a thirdm-sequence and a fourth m-sequence. Generator polynomials of the firstm-sequence and the third m-sequence are the same. Generator polynomialsof the second m-sequence and the fourth m-sequence are the same. Arelative shift value between the first m-sequence and the secondm-sequence is m₁, and a relative shift value between the thirdm-sequence and the fourth m-sequence is m₂, where m₁≠m₂(mod N). Thefirst m-sequence, the second m-sequence, the third m-sequence, and thefourth m-sequence each have a length of N, and N is a positive integergreater than 1.

The processing unit 903 is configured to process the first receivesignal and the second receive signal based on the local synchronizationsignal sequence.

Optionally, the first local synchronization signal sequence is asequence obtained based on the first Gold sequence, the first Goldsequence is the sequence generated based on the first m-sequence f₁(n)and the second m-sequence f₂(n). The second local synchronization signalsequence is a sequence obtained based on the second Gold sequence. Thesecond Gold sequence is the sequence generated based on the thirdm-sequence f₃(n) and the fourth m-sequence f₄(n), and the first Goldsequence, the first m-sequence, and the second m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₁((n+m+k)mod N)+f₂((n+k)modN))mod 2, where y_(m,k)(n) is the first synchronization signal sequence,g_(m,k)(n) is the first Gold sequence, and the relative shift valuebetween the first m-sequence and the second m-sequence is m₁. The secondGold sequence, the third m-sequence, and the fourth m-sequence satisfyy_(m,k)(n)=1−2·g_(m,k)(n), g_(m,k)(n)=(f₃((n+m+k)mod N)+f₄((n+k)modN))mod 2, where y_(m,k)(n) is the second synchronization signalsequence, g_(m,k)(n) is the second Gold sequence, and the relative shiftvalue between the third m-sequence and the fourth m-sequence is m₂,where n=0, 1, 2, . . . , N−1, k=0, 1, 2, . . . , N−1, m=0, 1, 2, . . . ,N−1, and k is a cyclic shift value. The generator polynomials of thefirst m-sequence and the third m-sequence are the same and areg₁(x)=Σ_(i=0) ^(K)a_(i)·x^(i), a_(K)=1, a₀=1, the generator polynomialsof the second m-sequence and the fourth m-sequence are the same and areg₂(x)=Σ_(i=0) ^(K)b_(i)·x^(i), b_(K)=1, b₀=1, and m₁≠m₂(mod N) issatisfied.

It may be understood that, for the first local synchronization signalsequence, the second local synchronization signal sequence, the firstm-sequence, the second m-sequence, the third m-sequence, and the like inthis embodiment, refer to related descriptions in the foregoingembodiments.

In this embodiment of this application, the user equipment processes thefirst receive signal and the second receive signal respectively by usingthe generated first local synchronization signal sequence and secondlocal synchronization signal sequence that have a small correlationvalue, that is, the user equipment processes the first reception signaland the second reception signal respectively by using a local primarysynchronization signal sequence and a local secondary synchronizationsignal sequence, to reduce a probability of false detection of a localsecondary synchronization signal and a local primary synchronizationsignal, thereby improving performance of detecting the first receivesignal and the second receive signal.

Referring to FIG. 10, another embodiment of a network device in theembodiments of this application includes:

a generation unit 1001, configured to generate a first synchronizationsignal sequence and a second synchronization signal sequence, where thesecond synchronization signal sequence is a sequence obtained based on afirst m-sequence and a second m-sequence. A relative shift value betweenthe first m-sequence and the second m-sequence is m, a cyclic shiftvalue is p, a value range of p does not include a cyclic shift value kstrongly correlated to the first synchronization signal sequence, andthe first m-sequence and the second m-sequence each have a length of N.A mapping unit 1002, configured to: map the first synchronization signalsequence onto M subcarriers in a first time unit to obtain a firstsynchronization signal, and map the second synchronization signalsequence onto M subcarriers in a second time unit to obtain a secondsynchronization signal, where M and N are positive integers greaterthan 1. A sending unit 1003, configured to send the firstsynchronization signal and the second synchronization signal.

In this embodiment of this application, the network device generates thefirst synchronization signal sequence and the second synchronizationsignal sequence that have a small correlation value, namely, a primarysynchronization signal sequence and a secondary synchronization signalsequence, to reduce cross-correlation between a secondarysynchronization signal and a primary synchronization signal, therebyreducing interference caused to a primary synchronization signal by asecondary synchronization signal in another cell or in a local cell.

Referring to FIG. 1 1, another embodiment of user equipment in theembodiments of this application includes a receiving unit 1 101, ageneration unit 1 102 and a processing unit 1 103:

The receiving unit 1 101, configured to receive a first receive signaland a second receive signal. The generation unit 1 102, configured togenerate local synchronization signal sequences, where the localsynchronization signal sequences includes a first local synchronizationsignal sequence and a second local synchronization signal sequence. Thesecond local synchronization signal sequence is a sequence obtainedbased on a first m-sequence and a second m-sequence. A relative shiftvalue between the first m-sequence and the second m-sequence is m, acyclic shift value is p, a value range of p does not include a cyclicshift value k strongly correlated to the first synchronization signalsequence, the first m-sequence and the second m-sequence each have alength of N, and N is a positive integer greater than 1. The processingunit 1 103, configured to process the first receive signal and thesecond receive signal based on the local synchronization signalsequence.

It may be understood that, for the first synchronization signalsequence, the second synchronization signal sequence, and the like inthis embodiment, refer to related descriptions in the foregoingembodiments.

In this embodiment of this application, the user equipment processes thefirst receive signal and the second receive signal respectively by usingthe generated first local synchronization signal sequence and secondlocal synchronization signal sequence that have a small correlationvalue, that is, the user equipment processes the first reception signaland the second reception signal respectively by using a local primarysynchronization signal sequence and a local secondary synchronizationsignal sequence, to reduce a probability of false detection of a localsecondary synchronization signal and a local primary synchronizationsignal, thereby improving performance of detecting the first receivesignal and the second receive signal.

In the embodiments, the first synchronization signal is a primarysynchronization signal, and the second synchronization signal is asecondary synchronization signal. The first local synchronization signalis a local primary synchronization signal, and the second localsynchronization signal is a local secondary synchronization signal. Theprimary synchronization signal is used to determine basic time andfrequency synchronization or a channel center. The secondarysynchronization signal is used to determine cell identificationinformation.

FIG. 6 to FIG. 1 1 describe the network device and the user equipment inthe embodiments of this application in detail from a perspective of amodular function entity, and the following describes the network deviceand the user equipment in the embodiments of this application in detailfrom a perspective of hardware processing.

FIG. 12a is a schematic structural diagram of user equipment accordingto an embodiment of this application. Referring to FIG. 12a , when anintegrated unit is used, FIG. 12a is a possible schematic structuraldiagram of the user equipment in the foregoing embodiments. The userequipment 1200 includes a processing unit 1202 and a communications unit1203. The processing unit 1202 is configured to control and manage anaction of the user equipment. For example, the processing unit 1202 isconfigured to support the user equipment in performing step 201 and step202 in FIG. 2, and/or configured to perform another process in atechnology described in this specification. The communications unit 1203is configured to support the user equipment in communicating withanother network entity. The user equipment may further include a storageunit 1201, configured to store program code and data of the userequipment. Optionally, the storage unit 1201 may store variousm-sequences, synchronization signal sequences, synchronization signals,generator polynomials, or recursion formulas mentioned in the foregoingembodiments, parameters used to generate the synchronization signals orthe synchronization signal sequences, or the like.

The processing unit 1202 may be a processor or a controller, forexample, may be a central processing unit (central processing unit,CPU), a general-purpose processor, a digital signal processor (digitalsignal processor, DSP), an application-specific integrated circuit(application-specific integrated circuit, ASIC), a field programmablegate array (field programmable gate array, FPGA) or another programmablelogical device, a transistor logical device, a hardware component, orany combination thereof. The processing unit 1202 can implement orperform various examples of logic blocks, modules, and circuitsdescribed with reference to content disclosed in this application. Theprocessor may also be a combination that implements a computationfunction, for example, including one or more microprocessors or acombination of a plurality of microprocessors, or a combination of a DSPand a microprocessor. The communications unit 1203 may be acommunications interface, a transceiver, a transceiver circuit, or thelike. The communications interface is a collective term, and may includeone or more interfaces, for example, transceiver interfaces. The storageunit 1201 may be a memory.

When the processing unit 1202 is a processor, the communications unit1203 is a communications interface, and the storage unit 1201 is amemory, the user equipment in this embodiment of this application may beuser equipment shown in FIG. 12 b.

Referring to FIG. 12b , the user equipment 1210 includes a processor1212, a communications interface 1213, and a memory 121 1. Optionally,the user equipment 1210 may further include a bus 1214. Thecommunications interface 1213, the processor 1212, and the memory 121 1may be connected by using the bus 1214. The bus 1214 may be a peripheralcomponent interconnect (peripheral component interconnect, PCI) bus, anextended industry standard architecture (extended industry standardarchitecture, EISA) bus, or the like. The bus 1214 may be classifiedinto an address bus, a data bus, a control bus, and the like. Forconvenience of representation, only one bold line is used forrepresentation in FIG. 12b , but it does not indicate that there is onlyone bus or one type of bus. Optionally, the memory 121 1 may storevarious m-sequences, synchronization signal sequences, synchronizationsignals, generator polynomials, or recursion formulas mentioned in theforegoing embodiments, parameters used to generate the synchronizationsignals or the synchronization signal sequences, or the like.

FIG. 13 is a schematic structural block diagram of a network deviceaccording to an embodiment of this application. Referring to FIG. 13,FIG. 13 is a schematic structural diagram of a network device accordingto an embodiment of this application. There may be a great differencefor the network device 1300 due to different configurations orperformance. The network device 1300 may include one or more centralprocessing units (Central processing units, CPU) 1301 (for example, oneor more processors), one or more memories 1309, and one or more storagemedia 1308 (for example, one or more mass storage devices) for storingapplication programs 1307 or data 1306. The memory 1309 and the storagemedium 1308 may be transient storages or persistent storages. A programstored in the storage medium 1308 may include one or more modules (notshown), and each module may include a series of instruction operationsin a server. Further, the processor 1301 may be configured tocommunicate with the storage medium 1308, and perform a series ofinstruction operations in the storage medium 1308 in the network device1300. Optionally, the memory 1309 or the storage medium 1308 may storevarious m-sequences, synchronization signal sequences, synchronizationsignals, generator polynomials, or recursion formulas mentioned in theforegoing embodiments, parameters used to generate the synchronizationsignals or the synchronization signal sequences, or the like.

The network device 1300 may further include one or more power supplies1302, one or more wired or wireless network interfaces 1303, one or moreinput/output interfaces 1304, and/or one or more operating systems 1305such as Windows Server™, Mac OS X™, Unix™, Linux™, and FreeBSD™.

All or some of the foregoing embodiments may be implemented throughsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, the embodiments may be implementedcompletely or partially in a form of a computer program product.

The computer program product includes one or more computer instructions.When the computer program instructions are loaded and executed on acomputer, the procedures or functions according to the embodiments ofthis application are all or partially generated. The computer may be ageneral-purpose computer, a dedicated computer, a computer network, oranother programmable apparatus. The computer instructions may be storedin a computer-readable storage medium or may be transmitted from acomputer-readable storage medium to another computer-readable storagemedium. For example, the computer instructions may be transmitted from awebsite, computer, server, or data center to another website, computer,server, or data center in a wired (for example, a coaxial cable, anoptical fiber, or a digital subscriber line (DSL)) or wireless (forexample, infrared, radio, or microwave) manner. The computer-readablestorage medium may be any usable medium accessible by a computer, or adata storage device, such as a server or a data center, integrating oneor more usable media. The usable medium may be a magnetic medium (forexample, a floppy disk, a hard disk, or a magnetic tape), an opticalmedium (for example, a DVD), a semiconductor medium (for example, asolid state disk (SSD)), or the like.

It may be clearly understood by persons skilled in the art that, for thepurpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiments. The foregoingembodiments may be referenced or supplemented to each other.Understanding is not affected and details are not described hereinagain.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual requirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit. Theintegrated unit may be implemented in a form of hardware, or may beimplemented in a form of a software functional unit.

When the integrated unit is implemented in the form of a softwarefunctional unit and sold or used as an independent product, theintegrated unit may be stored in a computer-readable storage medium.Based on such an understanding, the technical solutions of thisapplication essentially, or the part contributing to the prior aft, orall or a part of the technical solutions may be implemented in the formof a software product. The software product is stored in a storagemedium and includes several instructions for instructing a computerdevice (which may be a personal computer, a server, or a network device)to perform all or a part of the steps of the methods described in theembodiments of this application. The foregoing storage medium includes:any medium that can store program code, such as a USB flash drive, aremovable hard disk, a read-only memory (read-only memory, ROM), arandom access memory (random access memory, RAM), a magnetic disk, or anoptical disc.

The foregoing embodiments are merely intended for describing thetechnical solutions of this application, but not for limiting thisapplication. Although this application is described in detail withreference to the foregoing embodiments, persons of ordinary skill in theart should understand that they may still make modifications to thetechnical solutions described in the foregoing embodiments or makeequivalent replacements to some technical features thereof, withoutdeparting from the spirit and scope of the technical solutions of theembodiments of this application.

What is claimed is:
 1. A method for wireless communication, comprising:obtaining a first synchronization sequence s(n); obtaining a secondsynchronization signal sequence y(n) that satisfies:y(n)=[1−2·f ₁((n+k ₁)mod 127)]·[1−2·f ₂((n+k)mod 127)], where n is aninteger, n=0, 1, . . . 126, k is an integer and k<127, and k₁ is aninteger and k₁<253; transmitting a primary synchronization signal and asecondary synchronization signal to a user equipment, the primarysynchronization signal being based on the first synchronization signalsequence, and the secondary synchronization signal being based on thesecond synchronization signal sequence.
 2. The method according to claim1, wherein the first synchronization sequence s(n) is based on a firstsequence c(n), and a recursion formula of the sequence c(n) satisfies:c(n+7)=(c(n+4)+c(n))mod
 2. 3. The method according to claim 2, whereinone of sequences f₁(n) or f₂(n) has a same recursion formula as thesequence c(n).
 4. The method according to claim 2, wherein the sequencec(n) satisfies:{c(6),c(5),c(4),c(3),c(2),c(1),c(0)}={1,1,1,0,1,1,0}.
 5. The methodaccording to claim 2, wherein the sequence c(n) is: {1 1 1 1 1 1 0 0 0 01 1 1 0 1 1 1 1 0 0 1 0 1 1 0 0 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 1 1 10 1 0 1 1 0 1 1 0 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 0 1 1 1 0 0 1 1 1 0 0 11 1 1 0 1 1 0 1 0 0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 1 0 0 1 0 1 0 0 1 1 1 00 1 1 1 1 0 1 1 0}.
 6. The method according to claim 2, wherein thefirst synchronization sequence s(n) satisfies one of:s(n)=1−2·c((n)mod 127);s(n)=1−2·c((n+43)mod 127); ors(n)=1−2·c((n+86)mod 127).
 7. The method according to claim 2, whereinthe first synchronization sequence s(n) is: {−1 −1 −1 −1 −1 −1 1 1 1 1−1 −1 −1 1 −1 −1 −1 −1 1 1 −1 1 −1 −1 1 1 −1 1 1 −1 1 1 1 −1 1 1 −1 −1 11 1 −1 1 −1 −1 −1 1 −1 1 −1 −1 1 −1 −1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 −1 1−1 1 1 −1 −1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1 −1 −1 1 −1 1 1 1 1 −1 1−1 1 −1 1 −1 −1 −1 −1 −1 1 −1 1 1 −1 1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1−1 −1 1}.
 8. The method according to claim 1, wherein a generatorpolynomial of one of the sequences f₁(n) or f₂(n) is g(x)=x⁷+x⁴+1.
 9. Adevice for wireless communication, comprising: a processor, configuredto obtain a first synchronization sequence s(n); the processor furtherconfigured to obtain a second synchronization signal sequence y(n) thatsatisfies:y(n)=[1−2·f ₁((n+k ₁)mod 127)]·[1−2·f ₂((n+k)mod 127)], wherein n is aninteger, n=0, 1, . . . 126, k is an integer and k<127, and k₁ is aninteger and k₁<253; a transceiver, configured to transmit a primarysynchronization signal and a secondary synchronization signal to a userequipment, wherein the primary synchronization signal is based on thefirst synchronization signal sequence and the secondary synchronizationsignal is based on the second synchronization signal sequence.
 10. Thedevice according to claim 9, wherein the first synchronization sequences(n) is based on a first sequence c(n), and a recursion formula of thesequence c(n) satisfies: c(n+7)=(c(n+4)+c(n))mod
 2. 11. The deviceaccording to claim 10, wherein one of sequences f₁(n) or f₂(n) has asame recursion formula as the sequence c(n).
 12. The device according toclaim 10, wherein the sequence c(n) satisfies:{c(6),c(5),c(4),c(3),c(2),c(1),c(0)}={1,1,1,0,1,1,0}.
 13. The deviceaccording to claim 10, wherein the sequence c(n) is: {1 1 1 1 1 1 0 0 00 1 1 1 0 1 1 1 1 0 0 1 0 1 1 0 0 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 1 11 0 1 0 1 1 0 1 1 0 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 0 1 1 1 0 0 1 1 1 0 01 1 1 1 0 1 1 0 1 0 0 0 0 1 0 1 0 1 0 1 1 1 1 1 0 1 0 0 1 0 1 0 0 1 1 10 0 1 1 1 1 0 1 1 0}.
 14. The device according to claim 10, wherein thefirst synchronization sequence s(n) satisfies one of:s(n)=1−2·c((n)mod 127);s(n)=1−2·c((n+43)mod 127); ors(n)=1−2·c((n+86)mod 127).
 15. The device according to claim 9, whereinthe first synchronization sequence s(n) is: {−1 −1 −1 −1 −1 −1 1 1 1 1−1 −1 −1 1 −1 −1 −1 −1 1 1 −1 1 −1 −1 1 1 −1 1 1 −1 1 1 1 −1 1 1 −1 −1 11 1 −1 1 −1 −1 −1 1 −1 1 −1 −1 1 −1 −1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 −1 1−1 1 1 −1 −1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1 −1 −1 1 −1 1 1 1 1 −1 1−1 1 −1 1 −1 −1 −1 −1 −1 1 −1 1 1 −1 1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1−1 −1 1}.
 16. The device according to claim 9, wherein a generatorpolynomial of one of the sequences f₁(n) or f₂(n) is g(x)=x⁷+x⁴+1.
 17. Anon-transitory computer-readable medium, comprising instructions, thatwhen executed by one or more processors, cause the one or moreprocessors to perform the steps of: obtain a first synchronizationsequence s(n); obtain a second synchronization signal sequence y(n) thatsatisfies:y(n)=[1−2·f ₁((n+k ₁)mod 127)]·[1−2·f ₂((n+k)mod 127)], where n is aninteger, n=0, 1, . . . 126, k is an integer and k<127, and k₁ is aninteger and k₁<253; transmit a primary synchronization signal and asecondary synchronization signal to a user equipment, wherein theprimary synchronization signal is based on the first synchronizationsignal sequence and the secondary synchronization signal is based on thesecond synchronization signal sequence.
 18. The non-transitorycomputer-readable medium according to claim 17, wherein the firstsynchronization sequence s(n) is based on a first sequence c(n), and arecursion formula of the sequence c(n) satisfies:c(n+7)=(c(n+4)+c(n))mod
 2. 19. The non-transitory computer-readablemedium according to claim 18, wherein one of sequences f₁(n) or f₂ (n)has a same recursion formula as the sequence c(n).
 20. Thenon-transitory computer-readable medium according to claim 18, whereinthe sequence c(n) satisfies:{c(6),c(5),c(4),c(3),c(2),c(1),c(0)}={1,1,1,0,1,1,0}.
 21. Thenon-transitory computer-readable medium according to claim 18, whereinthe sequence c(n) is: {1 1 1 1 1 1 0 0 0 0 1 1 1 0 1 1 1 1 0 0 1 0 1 1 00 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 1 1 1 0 1 0 1 1 0 1 1 0 0 0 0 0 1 10 0 1 1 0 1 0 1 0 0 1 1 1 0 0 1 1 1 0 0 1 1 1 1 0 1 1 0 1 0 0 0 0 1 0 10 1 0 1 1 1 1 1 0 1 0 0 1 0 1 0 0 1 1 1 0 0 1 1 1 1 0 1 1 0}.
 22. Thenon-transitory computer-readable medium according to claim 18, whereinthe first synchronization sequence s(n) satisfies one of:s(n)=1−2·c((n)mod 127);s(n)=1−2·c((n+43)mod 127); ors(n)=1−2·c((n+86)mod 127).
 23. The non-transitory computer-readablemedium according to claim 17, wherein the first synchronization sequences(n) is: {−1 −1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 1 −1 −1 −1 −1 1 1 −1 1 −1−1 1 1 −1 1 1 −1 1 1 1 −1 1 1 −1 −1 1 1 1 −1 1 −1 −1 −1 1 −1 1 −1 −1 1−1 −1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 −1 1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 1 1−1 −1 −1 −1 1 −1 −1 1 −1 1 1 1 1 −1 1 −1 1 −1 1 −1 −1 −1 −1 −1 1 −1 1 1−1 1 −1 1 1 −1 −1 −1 1 1 −1 −1 −1 −1 1 −1 −1 1}.
 24. The non-transitorycomputer-readable medium according to claim 17, wherein a generatorpolynomial of one of the sequences f₁(n) or f₂(n) is g(x)=x⁷+x⁴+1. 25.The method according to claim 3, wherein a recursion formula of anotherone of sequences f₁(n) or f₂(n) satisfies: c(n+7)=(c(n+1)+c(n))mod 2.26. The device according to claim 11, wherein a recursion formula ofanother one of sequences f₁(n) or f₂(n) satisfies:c(n+7)=(c(n+1)+c(n))mod
 2. 27. The non-transitory computer-readablemedium according to claim 19, wherein a recursion formula of another oneof sequences f₁(n) or f₂(n) satisfies: c(n+7)=(c(n+1)+c(n))mod 2.